This situation is not good, he is dismissing your concerns, apoarently expects you to be the maid to his sons, is defending their poor behavior and worst of all, appears to think all this is fine.  The only good news is that you are not married.  I would make an exit plan and leave him to live with his 2 slobs.  If you stick around, I don't see this getting better.  For heaven's sake, use birth control, you don't want to bring your dear baby into this.

Well at least you're not married yet or have any kids by him. I'm married and we just had a baby. I was 41 and not supposed to be able to have anymore children but it happened and I see him as a blessing. My husband is the same way with his son11. Although he tries to get him to pick up after himself it never lasts. Each time he comes here he's smelly and lays on the couch or in the babies room glutting junk food. He won't eat anything I fix and is allowed to eat pizza and chips because that's all he likes. I tried to have some sort of relationship with him in the beginning but I got tired of his sloppy lazy entitled ways and I disengaged since dh refuses to parent him. I say that you start speaking up again (otherwise you'll be miserable) and tell your so that you're not a monster because you want them to clean up after themselves. That it's your home too. If he doesn't change and sadly I suspect that he won't then I'd get out of there and never look back. After what I've dealt with and still deal with I wish I'd have got out sooner. Now it's gonna be harder for me. 

Well here is your preview of how he will parent your future child.  Not good! You'll always be the bad cop trying to instill normal values.  And your child will wonder why they have rules and the other kids don't ; how unfair ! 
 

I imagine your bf sucks at other realms of parenting not just the cleaning up? It's not worth the headache , trust me.  I've lived it  over a decade and had to move out due to poor parenting and an awful teen.  Things evolve and get worse as these kids turn into teens and become bolder and harder to manage.  
 

my advice is run while you still can.  Find a simplier situation. 

Your SO doesn't want you telling his kids what to do and isn't interested in your ideas about how to run the household.   Don't do this - find someone who values you as a partner - this situation will not improve.  If you  want to stay - disengage- maybe his kids will launch at 18.  Sorry it sounds so harsh but this situation is not uncommon.

Haha... well, my suggestion would be to find a new BF.  I mean... his kids sound disrespectful, lazy and a bit meanspirited.  HE has not been a stellar father with zero expectations or consequences for his kids... and when you had the audacity to ask him to get his kids to rise to a higher level of behavior.. he acts like YOU are the problem and puts YOU down by telling you he thought you were lazy basically.

The best predicter of future success is the past behavior ... and clearly, you are seeing the results of his parenting right now.. even his current parenting.  he is more than willing to put you under the bus vs setting reasonable rules for his teen kids.

So, at 15/16, it is really unlikely to get better for you with his kids... they are likely very set in their patterns at this point.  At best you get a dual system where any kid you have will have different rules and expectations.. but I expect your SO will also expect YOU to be the primary parent to that child and will likely do little except for some fun stuff.

We have also seen here where a Bio parent still favors his first bios.. and the child with the sp becomes almost a 2nd class citizent.

I think I would be happy that at this point it's just a promise ring... and perhaps it's time to rethink that promise because he is giving you a load of red flags right now.

I don't think this is the relationship for you.

I'd be inclined to find someone else to father my potential children. This guy is neither a good parent nor a good partner.

Just curious...why aren't you working? And how long have you not been? Do you have a trust fund/large savings or is your bf supporting you? 

If he is supporting you, perhaps he thinks you should be responsible for the home - and to a point, I get it. Now, that being said it does not mean his kids should be slobs and not pick up after themselves. Nor does it mean they can be loud all hours and wake people up (do they not also wake him up, or are you a light sleeper?).

If he wants to let them order in and pay for it... who cares. Given their age, any children you have probably won't be affected - unless his kids are still living with you into adulthood and they tell your child. You will have "more say" with your child. 

But. Tbh, your bf kinda sounds like a jerk. Are you sure you want to continue on and have kids with someone that doesn't care what you think?