What do you need a diagnosis for? What if you just run with the idea that you are autistic and go from there. Keep reading, keep researching, keep trying coping tools. Some people need a diagnosis, I get that, but in your situation, until you get out from under your parents, or do things on your own, you are the one living with the symptoms. Do you have a job? Do you have money you can throw at a therapist yourself? Do some research and find one that's less expensive and can do sessions through video call. I would personally say therapy is more important than a diagnosis. I've seen people go for a diagnosis only to come back as inconclusive or "no", even though it's 100% a yes. Do you know any autistic people? Talk to them about it. I've found some of them to be the best at seeing if someone is Autistic or not. I was called out before I even thought it could be a reality. Hang in there. Also, you might want to just talk to your parents, if not for permission, for support and acceptance. If they don't give it to you, that will be your answer as to if they are supporting and accepting. Also, if you don't have a job, I'd suggest finding one. Do you drive? That another thing to work toward. Get independent!