I think I'm mentally ill?

Find another adult who you trust and tell them about your problem. If you can't find one, call a mental health clinic and explain that you need help, but that your parents aren't supportive. Don't be embarred, as they can guide you to good resources. You're right, a psychiatrist (or psychologist or social worker) is needed to help diagnose your symptoms and figure out the best course of treatment to get you feeling better. I hope you get some help, and I'm sorry your parents aren't there for you.