I agree with you whoswho... and incidentally, your opinion absolutely does count, 17 or not. Teenagers by definition are more moody, self-centered, and dramatic than adults. Part of it is related to hormones, part of it is the learning curve. It's a normal part of development.

However, when your "mood swings" are not triggered by anything or when they are accompanied by a significant change in functioning (ie you don't get out of bed to go to school/work, or you're having suicidal thoughts or actions) then it's not normal and it's definitely something you need to talk to someone about. It doesn't have to be bipolar disorder, or depression, or any other name, it's simply Not Normal. If nothing else, it seems like you're disturbed enough by the situation that you should talk to someone. The teenage years suck, but you're almost through. Hang in there!!!