Plan B

I had sex a few weeks ago and he took the condom off and got cum everywhere. Now it way too close, in fact I'm sure it ended up inside of me. So the next day I got the morning after pill, just to be safe. My next period was a week early and so light and short, the pharmacist said it could change the way my next period was and to take a pregnancy test anyway. I know it's silly but I'm actually freaking out because I know you can still get your period when you're pregnant, it's just not as full on.