I'm 13 and started two years ago but mymy period has lasted 2 months and is still going also if.i do small excersize-like things i'm out of breath?

2 months: 2 months is too long for you to bleed. If you have heavy bleeding you could have developed anemia. This is called dysfunctional uterine bleeding and the likely cause is an imbalance in your hormones. Other problems such as a low thyroid and trouble with clotting can cause the same problem. See your doctor very soon for an exam and investigations.