Help? What do you think?

I have a question this week is supposed to be my period. But the systoms this time has been worse than any time before.I have been exhausted badly lately. The first day it was a little bit of brown clots but since its just barely a light pink spotting or nothing at all. I am sexually active but I've been on the same birthcontrol for over 3 months. Ive always have a heavy flow so this never happened before. Has this happened to ayone else? Does anyone know what it could be?