My parents don't believe that I'm bipolar. But I think its obvious. And I have a lot of symptoms. How can I get it official. I have friends that agree.

See psychiatrist. Seeing a psychiatrist for comprehensive assessment is your best way to get a clear diagnosis. Share with the psychiatrist your areas of concern -- and be completely up-front with the symptoms you're referring to. The additional clinical information you've provided indicates that you're taking methylphenidate, so it's possible you're already working with a psychiatrist. If not, please do.
It is very important. To go beyond self- diagnosing if you believe you have a serious mental health problem. I suggest that you write your symptoms down ; calmly go over them w your parents. Ask for a formal psychiatric diagnosis. See that you have depression listed. Has that been formally diagnosed or self diagnosed? Psychiatric evaluation is the best way for you ; your parents to know if you have a bipolar disorder.