It is very important to feel at home where you live, no matter the size of the building. If you don't have a good feeling in your own home, then you have a right to change it. Otherwise, you can't be at peace, and that trickles into everything that you touch. You are NOT being selfish. It's not about putting up curtains. I never had to have the "finest" place to live, but I need to feel comfortable and clean in it, and that's not always resolved with just wiping it down.
I read your earlier post, and I was trying to give your husband the benefit of the doubt. Do you mean to tell me that you guys don't even pay rent, and he can't bring himself to entertain a conversation about moving to a place that feels good to you??? Sorry, Honey, but that ain't right. I have a feeling that when it's time for your daughter to go to school, he'll probably be fine with her going public. If the schools are good in your area, do something else with that money. Save it. Those two kids need separate spaces; if you can give them separate bedrooms, then you absoolutely should.
If you are paying no rent and can't afford to move, then that's a different story, but this doesn't sound like that's the case. It sounds more like he wants to be controlling...and that he never really grew up. He might be afraid to venture out on his own, away from his parents' shelter. If that's the case, then he should not have taken on wife and children.
I don't mean to disparage your husband; I'm sure that he's got plenty lovely characteristics. This seems pretty basic, though.
Also, be careful with the talk of waiting for his parents to die. He should not put you in a position to start fantasizing.... Besides that, you two don't seem to be so terribly young. By the time they go, you'll probably be not too, too far behind. You want to live your life now. You want to lay your foundation NOW...and enjoy it while your children are young and you can do so as a family. Twenty years from now is when you should be enjoying the fruits of your years of labor. Not that you'll be retired--sorry if I'm making you sound O-L-D. He is essentially asking you to put your life on hold--not even asking but demanding--and there's nothing healthy in that. By the time 20 years have passed, you won't feel like building or restoring a home. In fact, if you're still with him (which probably won't be the case), you'll be ready to hit him in the head with a cast iron skillet. The whole thing is a lose-lose.