Im 20 years old,sexually active,no birth control, and ive always had a pretty regular period cycle. The past few months they have been just random. They almost NEVER happen on or around the day they "should" happen, its just a waiting game. A couple months ago i had a period that lasted 11 days. The next month i had one 7 day period,and 4 days later i had another 7 day period. Im not supposed to have another one until december 5th but a couple nights ago i started randomly bleeding heavily, but only for a few hours. If anyone knows what could possibly be going on please help!