i'm sorry, but i can't really agree with the whole living by their rules thing. there are so many things parents can do to make their children miserable, just because they think they're always right about what's best for... their own well-being? reputation? i don't know, really. my breasts were a b cup when i was 12, my mom wouldn't let me wear a bra because she thinks they're damaging (well, they really are to some extent, but...), and of course because she herself never liked the ones that existed when she was younger. this only damaged my mental health, really. try to guess how stigmatizing that really was when around other girls who were given bras as soon as their chest started to grow (they were all smaller than me). it was horrible, and everybody was convinces that i had the worst parents ever for not letting me conform. yet another reason to bully me, you see...
if a rule is damaging to a child, then the execution of it can be equaled to child abuse. of course i wouldn't say it that way to your parents, that would only make things much much worse. but if a rule is damaging to you, you really should enter negotiations in order to change it.
wering a binder in the house isn't too much of a point. your family won't see you any differently with or without it, and your chest needs a good break between each time you bind. you might want to center your negotiations around getting to bind when you go outside the house. either at school, or when meeting friends outside school.
you could also just rebel and find a good place to get your binder on and off when you leave the house on your own, but you should be prepared for some consequences if they find out. it might not be a good idea at all.
that's pretty much all i could think of. do consider consequences before attempting anything, both your mental and physical health are concerned in this case.