Hyperactive Thyroid, please help i'm only a teenager!?

You're right, they are the symptoms of hyperactive thyroid and it's really sensible to get it checked out. The doctor will probably order some simple blood tests which will tell clearly if your thyroid is working OK or not. However, I look at the results of this kind of test a lot, and most people with these symptoms don't have a hyperactive thyroid. Exactly the same symptoms can be caused by anxiety and depression, so you will probably get asked questions about this too.