What do i do if i have been bleeding for 12 days, i am 17 years old, on birth control and sexually active?

12 days=menorrhagia: A normal menstrual period should last about 7 days. But at 12 days we would classify this a menorrhagia (prolonged menstrual period). This could be caused by number of issues like clotting disorders, hormone imbalances or fibroids. I would suggest you speak with the doctor who prescribed the birth control pills in the first place.They will be able to conduct the proper tests to determine the cause