I am 16 years old and have had my period for about two 1/2 years. My period has always been irregular but this year it started to get regular. However, these past two months I have been having trouble with my period. I got my period and then two weeks later I got it again. Then following the second heavy period I have been getting light bleeding for about two weeks. I am pretty positive it isn't related to pregnancy or sexually transmitted diseases. I was just recently put on medication for depression/anxiety. I started with Prozac then switched to Effexor. Could this have anything to do with it? Or could it be something else?