So I have not gotten my period in 6 months. I know I am not pregnant if I was I would have a belly right now but I don't. It was about 6 months ago when I first had sex, the day that I did I was supposed to get my period but I didnt. Instead of getting my period I get this black discharge once or twice a month, and its not like my regular period its very light and black. What could it be? By the way I am 16 years old.