TMI PIC SORRY!

So I had sex one week before my period, I'm on the pill and he didn't cum inside me, what are the chances of being pregnant? My period was 3 days late which happened a good few times before and was never pregnant, And when it came today I just wanted to know if this was my period or Implantation bleeding? I've read that implantation is painless but I'm having really bad cramps? I'm really worried. Help please!