Bipolar Disorder!

Patient: I believe i have a pibolar disorder. Everything i have read on it, confirms the thought i might be bipolar. My mood swings, to severe depression, to feeling high at points, having episodes. And i have read what causes bipolar disorder, it runs in the family and from stressfull lifetime events, both which are true for me. And i took an online exam from a organiztation, and tested positive for it. how do i know for sure?