So i am on my second pack of birth control, i am taking Junel 1/20, its a 21 day set. After my first set i went straight on to the next set, to avoid my period until the end of the second pack. I take it at 10pm every night, i never missed a pill but i have taken it no later than an hour after i was supposed to. I started the new pack on the 8th and on the 11th i had sex with my boyfriend. Today, two days after sex, i started bleeding. It wasnt light enough to be spotting but it wasn't persistent enough to be my period, mind you im on the pill currently. Any ideas what it could be?