To tell you the truth, I would say that it is good that they don't put you in "special needs classes." It's quite possible that you don't need them. The reality is: being in Special Ed carries a stigma. It's probably better that you're in "regular classes."
I'm sorry that the school is not helping you, and that you're frustrated.
You're probably in a school district that has many kids, and many disabled kids. Unfortunately, high-functioning autism is, frequently, not seen as being a "priority" disorder like, say, Down's Syndrome.
I wish your parents would advocate more for you, so you could get some services--what sort of services do you think you need? What sort of trouble do you have academically in school?
What will help you in your life is getting your high school diploma. How long do you have left before you get that diploma?
I'm sorry you're going through hard times. Always remember: many 17-year-olds, even "normal" kids, go through problems. It's a tough age for many people.
I would say, if at all possible, that you should focus, first, on finishing high school. After you finish high school, things will probably get at least somewhat better for you.