What Causes Prolonged Heavy Periods While On Birth Control?

Hello, I am 20 years old and have been put on the birth control pill from my teens until now. Recently, within the last 5 or 6 cycles my period keeps coming every 10-14 days, and lasts about 5 days. I m highly concerned as this is not usual or normal for me and I have brought this up with my partitioner. I m a 2nd year RN student, highly stressed out. I was stressed out tonight because I have to do homework for the next 5 days straight then boom I got my period. So is it induced by stress?