I had unprotected sex with my boyfriend and immediately had the morning after pill 5 hours after that. One week later, while my boyfriend and were engaging in the act of sexual intercourse, i noticed that i am bleeding, I'm not sure whether what I had would count as a "bleed" (it was very light and lasted less than one day). What I want to know is: does any bleeding count as the first day of period? .... Anyways, I assumed it was and started taking birth control pills for the very FIRST time in my life.

I wasn't experiencing bleeding for the next 3 days, the bleeding came back in full fledged only after the aforementioned 3 days. So now i'm confused, when was the official first day of my menstrual cycle? I am worried because i've started having unprotected sex since going on the birth control pills since the first day i've taken it, and i know the prevention of pregnancy via BCP can only be effective if taken on the first day of menstrual cycle. Right now it's already the 19th day on the pill, and another 3 pills before i finish my first pack.

Please help.

ps: Sorry for the grammatical error.