I'm 17 years old. My periods are regular, usually heavy and last 6-8 days. My boyfriend and I have unprotected sex often. I think i had implantation bleeding but i'm unsure. The last time i bled it started with brown dark discharge and went to extremely light pinkish red bleeding from Jan 23-Jan 28th then stopped. it wasnt even enough though to get on a pad, and only showed up when i wiped. then feb 2nd i had pink spotting for an hour. That night i had sex and it hurt when he would go all the way in. But it went away. now my breasts are tender and my nipples are sore, i have light cramps and lower back pain. I took a pregnancy test on saturday(feb 2nd) but it was negative. Could i possibly be pregnant? could it have been too early to take a test? help, i need opinions on this....