Brown Vaginal Discharge- Pregnant?

I had sex a week and a half ago. We used a condom, but I felt worried because it was half off when he pulled out. So, I took Plan B two days after (which it said that it works up to 72 hrs after sex, so I was in the time frame). I don't really have any pregnancy symptoms except I'm peeing a little more than usual (or I'm just paranoid and keeping track?)... Anyways, I should be expecting my period sometime this week. But I realized that I have this brown vaginal discharge. It has some clots too. I looked it up online and it said that it could mean pregnancy! Which freaks me out. Could it possibly just mean that my period is on the way? I really don't have any other pregnancy symptoms and I took the emergency contraceptive as instructed.