Ok so I've been on birth control for 2 months now and I'm worried about pregnancy. So on the 3rd row of my last pack of birth control I had unprotected sex with my boyfriend he didn't ejaculate just some pre-cum came out. A week later I started my "period" on the placebo pill but, the blood was extremely minimal and a dark brown red color? My period barely lasted for three days! I'm used to heavy bleeding for around 7 days! Is this just how periods are on birth control or is it implantation bleeding? I did research on the internet and I'm really hoping this is not implantation bleeding. Also I started my second pack a little late 24 hours but had no break through bleeding and took the pills a little off (1 hour or so). My period is due in 4 days and I really don't want to be pregnant. Please help.