i don't really know what to say but I'm sorry for all of this you have to put up with. Your husband needs to step up to the plate as the father. You should shop for your kids together and he should do his own. I don't know your husband but it sounds like he does not except responsibility, is that why his daughter lived with her grandmother since 6 months and now he has you there

I feel for you. I don't know what your relationship with DH is like, but it sounds like he has made some bad decisions in his past, and he needs to be the one responsible for them. I know how hard it is to try to raise someone else's child, particularly when they are AWFUL! But, try to pretend that you adopted these kids, and not think of them as HIS and not yours. The animosity you feel toward them, and resentment that YOUR kid isn't getting what you want for him because THEY are taking everything will likely bleed into everything you do. You were right to think that with enough love and guidance these kids will blossom. But you have to put aside your personal feelings for the betterment of your family. If you want a good life for your two sons, you will HAVE to make a good life with your skids, too. Because in the end, if the 2 older kids are horrible, it won't matter how well you raise the younger 2, they will be influenced by their siblings. And your DH needs to be more involved. MAKE him take responsibility for his children. If they misbehave, HE has to punish them (even if you are the one standing behind him telling him what to do). And make a big deal of giving the skids presents and pointing out that you and their father are the ones raising them and providing for them. I promise you, if you can find it in your heart to accept these kids as your own, you will find the peace you have been searching for. It is going to be difficult to eliminate the resentment toward them and the hostility toward their BMs. And no one here would judge you if you were unable to overcome those obstacles. But, if you truly want what is best for your biological kids, teach them compassion through your actions toward their half sibs. It will reward you in the end.

I did this too, all too often we wait until we are too hard pushed, A DH can have no indication that we are not managing because often they are oblivious and are out working etc. so do not want to hear negative stuff when they come home.
I think that your desire for a daughter is influencing you though, I'd let that go for now. I am not saying give up on it by any means since it could be a reality, however, for the moment I'd focus on the children you have right now. You can stop cussing me out now...LOL
It's hell on wheels with SKids at times, believe me I know this! I had the delusion too that they would grow out of the crap in a stable, steady home too! DH was what they call a 'guilty daddy' and did not issue consequences for bad behaviors. I was the baddie!
I am not sure if your DH falls into the category of 'guilty daddy' or if he's just so damned busy working and has not noticed your struggles? Or, he could just not want the responsibility of children...in which case he REALLY needs a sharp learning curve!
I disengaged with SKids but they were older than yours at the time, younger kids really do need constant attention and if DH is at work then that's where he NEEDS to be during those hours. It's a drain on anyone to be taking care of kids, regardless of step or bio.
I felt in danger of losing my own self amidst all the chaos so I put more on my husband regarding the SKids, one day I was sick so I told him he'd have to take them with him to work! He took them and they broke the windshield on his truck, next day their mother came and took them. I had a migraine and I was debilitated by it. SD has ADHD, ODD and emerging borderline personality disorder and her twin brother just did not get a diagnosis but he is afflicted similarly. Hell on wheels as you well know!
Possible solutions...
I'd be 'busy' with some chores when they demand attention and tell them if they help you you can get to what they want quicker...if they do not want to help and are just bored and demanding then ask them if they'd rather to (insert occupying activity they can do on their own) and you'll be right with them when you are finished. That indirectly teaches them that they cannot have your attention on demand.
On a day when you and DH are both having a good day I would begin asking him questions about how he envisions the future, start with how much you are looking forward to retirement, or semi retirement after the kids are grown. Incidentally kids will grow up and leave regardless of how they are raised!
Then you could discuss the one with ADHD, refer positively to people who have made good and have the disorder, Richard Branson (of the Virgin brand) for one. I used that one! I joked that SD could become an entrepreneur and keep US in luxury! That lead onto a discussion on coping strategies with the disorder and DH and I agreed that she's a very intelligent girl. There are a lot of help sites online for parents and kids with ADHD. Strongly suggest that DH looks at some of them and that will clue him in, he may not have a clue about it? I didn't know anything about it until I was dealing with SD! I STILL do not know enough about it...LOL which is why I am suggesting that you and DH do some reading.
Some husbands really do have a misguided opinion on their role in their kids lives, a lot of homes are matriarchal and the poor husband just has to say 'yes dear', was DH raised that way?
With regard to the presents and the fairness of it, again, a discussion beforehand, under the guise of 'what shall WE get for the kids this year?'
It's important for parents to be working together and it takes a lot longer for step families to get to that stage because of pre concieved ideas that each person brings to the table.
I would also begin to foster the idea with them all that 'fair exchange is no robbery'. You really just have to be a BETTER master manipulater than everyone else...shhhh I did not say that and this paragraph will rip itself up and be chewed and swallowed within ten minutes of you reading it...
I wish you luck, what I'd like you to do for now is to eat well, rest when you can and stay hydrated! Look for something to smile about each day too...even if it's just 'damn that giveitago!'

I think stepparenting is hard enough without dealing with a DH who is a lazy parent and has his head firmly planted in the ground, who refuses to listen or address the issues HE has dumped in your lap.

This situation may be way more bearable if DH was a loving, fully engaged dad who was prepared to also make sacrifices for you so that you could be happier - including compromising on acitivies with skids, the room situation, giving you time on your own with bioson and for yourself and being responsible for disciplining and ensuring the skids are gracious to you for all that you do for them - but he doesnt, so its suffocating you. He isnt even prepared to listen to you, let alone actually DO something to ease the burden he created, so my dear its time to start realising your life is worth more than sacrificing it for individuals who just dont acknowledge, appreciate or try and give back to you.

The reason people marry is to enrich their lives - not with crap and stress - but for the better. Ok, we ALL have periods in our lives that arent kodak moments but to me your situation doesnt sound tenable long term. What happens if this grounds you down so much you cant be there for your children? You mention your bioson isnt receiving all that he should from you, and while I am not endorsing a bio VS step conflict, I am saying I disagree with the idea that because the skids havent got BM who are involved YOU have to be the one who suffers.

I urge you to stop. Stop doing what you are doing. Stop trying to discuss it with DH. All you are doing is upsetting yourself further because DH stonewalls you (he has shown you he doesnt want to hear it) and gives him the opportunity to blackmail and guilt you into things that HE wants. Is that a marriage or is that a dictatorship? From where I am sitting, if DH had a healthy perspective of marriage and parenting he would want to listen to you worries, soothe them for you and try and find ways which you all are happy (even more so given you are pregnant). I dont know why he doesnt want to, but am guessing he is genuinely believes the guff he spouts regarding your biokids or he thinks he is spread too think or he;s plain selfish and lazy.
Stop letting this man guilt you, his children are missing out massively because of his inability to deal with the mess and help sort out a means to resolve everything and by just giving in to him, and them, you are actively enabling DH to dodge this bullet.

There is a reason why "actions speak louder than words" is so well known, because its true.

Have you tried to disengage? I suggest you do this and take on the responsibility for your bio son and the child you are carrying, start putting your happiness and the responsibilities you signed up for first. The only way your happiness becomes a priority is if YOU give it importance.

You mention not being to provide certain things because of having to pay for skids - why? Thats DH's job. So stop giving and if you are at some point prepared to be generous and favour them with a gift/time then at a minimum I would expect attitudes to changes and thank yous. Remember you arent the BM, so your input isnt a given - its your choice. If the skids think daddy is so fantastic- then great - but they can go to him for things like lifts, new books/clothes, outings to the park (he doesnt work 24/7 so am sure can manage this). If daddy is in work, then they will have to wait until he is home to ask/do things. They have a tantrum? Ignore them and carry on with what you are doing. SM is on strike until everyone starts treating you in the manner you deserve and expect - including your husband.

DH doesnt like it? My response to him would be: Oh sorry I thought when you chose to have ss/sd, you made a lifelong commitment to them and WANTED to parent them. Doesnt seem that way atm, with you shirking it all onto me. I call that lazy. I call that uncaring. Oh and dont bother trying to blackmail me with MY children - its not like the last x years I have been 99% responsible for YOUR children, sorry, I must have hallucinated that...this is what is happening from now on and this is the only time I will be discussing it, so dont bother me with it. After all, its that what you have more or less been saying and doing when I have tried to discuss things with you. If you can do it, then so can I. And I am, watch me....

Then completely disengage. If (I say when) DH tries to blackmail you and says things to get a reaction (nasty things). Ignore him. Keep telling yourself while he is doing this, he is only doing it to get a rise and get out of his responsibilities. He isnt prepared to compromise and only if he demonstrates long term changes then I would discuss things with him.

These articles may help:

http://csmchat.weebly.com/disengaging.html

I suggest you write this letter to DH and carry out everything. You have the power here. I know it doesnt seem like you have, but ultimately DH relies on you to organise and see to the children. No small feight, but as a partnership he should be contributing to it and with the knowledge that you are doing a great job with children that arent yours.

Paste that smile on and keep thinking about the ease of burden and all that extra time/money you have to do whatever you want

Good luck!