Wellllll. You could go to a doctor and ask if your symptoms could be bipolar.

They should send you to someone who can diagnose you or help you. Or at least ask you questions. Give you questionnaires to fill. Though usually that happens at the psychiatrist's / therapist's. If they tell you to stop self-diagnosing (without doing any of the above), go to another doctor.

It is important to recognize it early. Best of luck to you!