My Parents Don't Care About My Mental Health

TW: My parents don't care about mental health. It was hard enough when it was just mood disorders (social anxiety/depression), but now, less than a year ago, my counselor diagnosed me with ADHD & mild autism (it doesn't feel official so I want to go to a psychologist; it feels wrong to say i'm autistic yet). My mom told me my social anxiety will go away by the time I graduate, but its worse than ever. My dad doesn't understand how it affects me and forces me to speak and yells at me for my faults that I don't have much control over (memory, losing things, not comprehending things and making simple mistakes/lack of common sense). My mom believes autism is caused by vaccines and that autism is an illness/bad thing. She's nice to autistic people, but she doesn't want or care to understand them or puts certain expectations on them (not acting weird or following social rules/norms). She and my dad don't know I've been diagnosed and I haven't fully accepted my diagnosis until it's from a psychologist. They aren't like abusive all the time. We laugh, love each other and try to have fun and hang out, but they don't want to know or understand their children. My stepmom even laughed when I told her I wanted to kms, her, my step aunt and step cousin. We get along now but I can't forget that or truly trust her bc of that. I'm afraid they will do my baby sister like that when they don't know how to handle her possible issues or that my brother will not get treatment and continue to be ignored. He has told me he's very depressed. I have selective mutism and I suspect he is suffering from it too now. We are somewhat similar, but were raised differently (he was punished more, I was more praised until a certain age).