Plan B, "period", still pregnant??

Okay so I'm not sure if I should really even be worried. But here's the story: I had sex a little over a month ago. It was a day before I ovulated but we used a condom. However, we were a little drunk and  didn't check for any holes or rips so I bought Plan B a little over 36 hours later. I got my "period" 2 weeks later which was two days early. It started out regularly. Filled pads and tampons but it only really lasted for a good 3 days and was definitely lighter and shorter than usual. But I didn't think much of it until now (a month later) because my boobs are really sore, I've gained some weight, and have a good amount of CM. I wasn't worried until multiple woman have said they recieved their period during early pregnancy. My period isn't due for another week but I took 2 hpt last week (both negative) and I'm just really scared my period won't come. Am I overreacting? Does this sound like a likely pregnancy risk?