bleeding after sex...? (TMI)

So, my boyfriend and I had sex on New Year's Day, and it was the day after my last placebo in the birth control pack.  There was a tiny bit of blood on the condom, but we dismissed it as leftover period blood.  But today, 1/4/17, right after sex, after I peed, I noticed brown blood on the toilet paper.  And a few hours later, when I peed again, there was brighter red blood on the toilet paper.  I googled this and saw that it's either stds or pregnancy.  But I've only been with my boyfriend, and we were both virgins, so STDs are out, and we always use a condom and pull out- and as previously mentioned: I am on the pill.  We've had sex before, so it's likely that my hymen was already broken, but it's possible that it wasn't. So does anyone have an idea of what's going on?