I wish I could tell you what your symptoms represent but the truth is that a trained professional is the one who has your answers. Bipolar is not always the easiest illness to diagnose correctly and self diagnosis is not recommended. But, it is great that you have identified what your symptoms are to help them make the diagnosis. This is not a good illness to go untreated for any length of time.
I have a son who is a little older than you. I would like him to be honest and direct should he be having the mood swings you are having. The tricky part is that there is no way they can be prepared for what you are going to tell them. Try not to let their first reaction deter you. Please be persistent though. It is very important that you recieve the help you need.
I wish that I had told someone so many years ago. It would have saved so much heartache and things that didn't need to happen. I know it is a hard thing to do but you sound like a very determined person. Please do not give up on yourself. If you find out that it is teenage behavior then all you have lost is an hour of your life talking to someone. Not a bad deal.
Good luck. I hope that things go well for you. Hang in there. There is help for you.
BTW I am no comparison to Petunia's link. As usual..