I'd suggest speaking to a therapist and trying to get to the bottom of it. A therapist can pretty much diagnose Bipolar or any other mental illness. But they will be able to work with you a lot more intensively to understand your circumstances and symptoms.
I think it would be jumping the gun to assume you need meds if anger is your only symptom.
You are going through your teenage years. Going from childhood to adulthood. It is a frustrating time as you try find yourself and stand up for what you believe and stand for. I think your anger 'issue' is quite common for someone your age.
I am really not against meds, but in your circumstance, I'd recommend looking at all other avenues first