Correct me if I'm wrong, but isn't your SO the one who said she wasn't looking for a co-parent and wanted to do this on her own? She just wanted a partner for her?

You already do more than you need to. Unlike most on here, she actively chose to be a single mom - warts and all. SHE is extremely lucky to have found a partner with no kids, no ex drama, no want to be an equal parent who will challenge her parenting choices. She doesn't get to decide to be a single parent and then try to dictate to you what duties of hers she doesn't want and expects you to take on.

If I were talking to your SO, I'd tell her this: SO, if you are now realizing that being a single parent is NOT what you want, then you need to communicate that with your partner. BUT, your partner is NOT required to accept the new terms of the relationship. You don't get to change things just because parenting got hard and you're jealous that your partner who didn't take on these responsibilities chooses not to share in them. Those are feelings YOU have to work out, not OP.

Feel free to share that with your partner, Boo. As for you, you seem like you're doing fine. You're kind to the kid, you help out when you want/it makes sense/in a way that helps your SO, and you stay in your lane like you've been asked. You're even coming here for advice, so bonus points to you. Don't let her gaslight you into thinking you're not doing enough when you're doing EXACTLY what you said you would do AND EXACTLY what SHE wanted you to do. If she wants to try and renegotiate the terms of your relationship, she can use her words and not be a dick about it.

To answer your first question- the role of the step parent is whatever the step parent feels comfortable with. For SS21 (Autistic), I am mom. 100%, I do doctors apts, I make sure he has clothes, I chase after him for chores. I worry about him. I love him. 

For SS17, eh... I started out more involved but being long distance meant that I got to be the "fun aunt". He would pop in for a few weeks. We did lots of fun things and he would leave. There wasn't much parenting. Due to BM2's alienation and SS's behavior, I won't even be fun aunt anymore. He is lucky if I cook dinner and include him. 

With what you are describing, I would never expect my husband to wake up for my bio's in the middle of the night (he is the stepdad). Unless there was an actual- we are going to the hospital emergency- I have always done my best to keep things quiet so he can sleep if there are any middle of the night issues (hasn't happened in years and they are teens now). When they were younger if we had a middle of the night sickness hit, I never went back in the bedroom and kept everything quiet and cleaned up. Those are my kids and my responsibility, not his. 

As for the bedwetting and screaming out- he needs a pull up diaper and a sound machine to help keep him asleep. He also needs to be told that he can't just scream in the middle of the night. He is being rude to the rest of the house. He is 7 not 2. He should be able to handle sleeping in his bed without issues! 

And expect their spouse or partner to be surrogate mummy or daddy for the absent/alienated or crappy other parent in their lives.

its not fair to ever expect this. When i met my husband, ss was 15.5 yrs old. His mum disowned him in the divorce and hubby had sole custody. Apparently my husband expected i be surrogate mummy because i was a great example of a nurturing mother. I told my husband it wasn't my fault his exwife was batshit crazy and neglected step kids but i should never be put in a position to place their priorities in life or care/maintenance above mine. Their wants dont take priority over mine

i was breastfeeding my newborn son whilst my husband was at work one day, hubby wanted me to give ss20 some money to pay for his glasses at optometrists. I told hubby i was breastfeeding and its a marathon time where my son would be non stop breastfeeding and in my arms several hrs so ss20 had to wait.

I remember my husband telling me to stop breastfeeding our newborn and go downstairs to give ss20 money. "NOOOOOOOOOOO!!" Was all hubby got followed by are you telling me to stop breastfeeding our newborn son (a priority) to give money to your disrespectful son who shuns us and emotionally abuses us with pleasure?? Because he can wait 4-7 hours till i feel ready to give money but he is not my priority right now or ever.

that set things in place for my husband and i reminded him this is what his son deserves and gets from me by treating me the way he has always done...

i did about 2-3 hrs later put money on the table downstairs and told my husband to message his kid to take it since he enjoys pretending I don't exist.

Your role is whatever you two work out your role should be. In my case, I was the "fun aunt", and while I helped DH with things occasionally, I was not a parent in any sense of the word.  I didn't want to be, and DH didn't want or expect me to be a parent. 

You and your GF need couples counseling to sort this out. Everything you post is about you not wanting to be a parent to her kid, and her absolutely wanting that. You two aren't on the same page at all. 

clearly she has different expectations of a partner.  Unless you can explain your own preferences.. and that you are not interested in being a partner in parenting her child?  you will continue to have conflicts.  If she needs her partner to do this then maybe she needs to find a different partner?

I'm saying this with all my feelings since you sound like a great person but your SO exhausts me.  She expects so much from you that she shouldn't.  Please think about relationship counselling as already suggested.

I think you need to accept that this may not be the relationship for you.

Some play no role at all, or they're the fun aunt, some take on more of a parental role.  My dh did expect me to take on the surrogate mother role.  I loved SS so at the time I was ok with that and I thought that was what I was supposed to do.  BM seemed fine with it too.  I think she just saw it as I cared about her child, was good to  him, tried to raise him right and she wanted him to turn out well, so she was ok with it.  I was given authority from both parents too and SS actually treated me with more respect than he did BM, MIL, and SIL.  He ran over them.  I think he resented that he couldn't run over me.  He did supposedly think of me as mom but you wouldn't know it by his actions leading up to me cutting him out.  

So, I'm one of the not successful stories here.  But that's me.  If taking on the parental role is not for you, then don't.  He is not your responsibility.  If she expects her partner to take on a parental role then she needs to find a partner willing to take on the role.  This isn't the relationship for you.  My own stepmother never took on the role of mom with me either. I already had parents but I did respect her as an authority figure because my parents raised me to respect my elders.  

SD used to call out for her dad in the middle of the night. If he didn't hear her, I'd wake him up. Never once did he expect me to get up for her, in fact he felt bad that my sleep was interrupted.

Your gf chose to be a mother, which includes getting up in the night to tend to her son. Not even asking, but expecting you to get up to look after him is absurd.

It really seems like this woman was just looking for someone to pass her parenting duties to.

Your partner could have chosen to have a child within the alliance of a domestic partnership.  But instead she chose to become a parent on her own.

Because....?

Because she didn't want the obligation of shared custody with another person?

Then you come along.  This child is not your responsibility.  Any favor you do for her is a gift and should be appreciated.

Hold your ground! 

Also, to add - lying down with a kid because they are scared at night isn't actually a need. If they pee that's one thing, but if your partner is getting up every night for bad dreams and getting in bed with him, that's not necessary. So to ask you to help with a *want* is especially bad. I know plenty of parents in intact families that don't allow this kind of thing. Single/divorced parents tend to allow more nonsense from what i've seen. 

If he is peeing every night, he needs to have his fluids limited a few hours before bed (but make sure he has enough early on), avoid certain things like caffeine and, in my son's case, watermelon, and be made to pee before bed. You mentioned in a previous blog that he always fights you on this. That's a tough one but maybe tell him if he refuses to pee before bed, he gets no electronics the next day or something. None of these things are for you to do, but just to illustrate that things can be done besides losing hours of sleep and if your partner refuses to do them, it's her own damn fault.