You are certainly in an unenviable position, but not a hopeless one. It certainly would make a huge difference if you parents listened to you rather than the doctor who suggested you be institutionalized. Your frustration and confusion are understandable and a normal reaction to circumstances like yours. This forum really is a great place to find someone to listen to and understand you.
However, I'm also sensing you are only telling us part of the story - the part where you get to be the victim. There is nothing wrong with that, and I can tell because I've done the same. The problem is doing this keeps you stuck as the victim rather than claiming your power. Another problem is that you didn't say things I think could be helpful. [EDIT - strike this] For example, have you been dx'ed with AS or other PDD? [End Edit]. Why were you institutionalized? (Aside from showing "the emotions!") I'm not suggesting you give your life's story or tell us things you would rather not.
I admit I may be completely wrong and I realize my strong tone may not be appropriate for a 15 year old. I think if I were to talk to you as a 15 year old and tell you how bad I think your situation is that it would not help you. With AS, the good news is you have the ability to adapt to society and still maintain your uniqueness. Part of what you are dealing with is what every teenager deals with, which is finding out who you are and how you fit in. In the end, you are who you say you are. You are far more powerful than you realize and far more capable than you imagine.
I think it's important you find someone to talk with who understands AS and who understands you; your reaching out in your post is an excellent step. People in this forum are great resources. I also think you should consider some form of therapy from a practitioner who deals with and understands AS and other autistic spectrum disorders. I wasted many years being a victim and blaming others and I don't wish that kind of life for anyone, and certainly not for you. Good luck to you.
** EDIT ** I see you were dx'd AS from your other post (Someone please tell me?). Must be the ADHD in me.
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"Freedom's just another word for nothing left to lose."
Kris Kristofferson, "Me and Bobby McGee"