I'm so sorry you're going through this

Seems your parents may have got the "parent of a disabled child syndrome" :/ I mean, raising a disabled child is a challenge and some parents seem to cope with it by making it part of their identity - but then the time comes when the child is no longer a child, they wants to cope with their life on their own - but that's stripping the parents of their long embodied part of identity! So they may unconciously fight to keep their child more disabled than they really is.
I may be completely wrong about you and your parents, I don't know your situation well enough. It's just something I've noticed happens worryingly often.
Society really needs a "Parental Licence" system, with tests and manuals.