I've been having sex since October 2012. The first time, I bled, but it didn't happen after that. Two weeks ago, I had sex again and there was a moment where I thought he went in to far, because it hurt. Three days later (a week before my period was due), I started bleeding. Every day it was light, a week later, I thought it was coming to a stop and I had sex again, it was a bit uncomfortable, but it didn't hurt. The next day, I got cramps, and what seems to be a normal period. What was the bleeding? Can I get my period twice in a row? (note that I've had sex with only one guy, and protected all times)

There's absolutely no way for anyone to tell you what's going on online. If this is a concern than the only suggestion is to see a doctor.

Just fyi, protection only lowers the risk, it doesn't eliminate the risk. No form of birth control is 100%, so if you're having sex, pregnancy is possible. So don't rule that out just because you're using protection.