Period or Pregnant

So I had sex about 2 weeks ago. We used a condom. Then a week later we had sex again, but that time bc I was having anxiety like usual, he bought me a plan b to make me chill out lol. I took the pill a few hours after sex. My period was due within the next couple of days. The day after that I had the WORST cramps of my life, but I wasn't bleeding, just hurting. That was Thursday. Today is Sunday and I woke up with watered blood. And I think it's my period. But at the same time I'm freaking out cause all of the sights say that bleeding is apart of pregnancy?!? My tits also hurt like a mofo and are tender around the nip, aerial, and tissue. WHAT DOES THIS ALL MEAN!?!?!?!?! -anxious girl