The diagnosis of bipolar disorder should be an extensive one. Ruling out anxiety disorders, depressive disorders, thyroid issues, post traumatic stress disorders. Many mental health professionals are reluctant to diagnose chronic mental health issues in younger people (people under 17-18) because hormonal changes, teen pressures and sociological issues can be major triggers for unbalanced behavior in persons who are not yet adults. It's best to talk to a counselor or teacher about your concerns or a doctor.