What Causes Heavy Vaginal Bleeding After Taking I Pill?

hi I had unprotected sex on sunday may 11,my bf came inside me. I took the morning after pill on may 13. I usually get my period on the 15. I got a bit of bleeding on Wednesday ,14, n I was bleeding just a bit on the following day Thursday.15, and Friday 16. on Saturday 17, I bleeded a lot more. n sunday ,18 and Monday 19, normal bleeding. and today Tuesday,20, I started bleeding really heavy, I don t know if its normal. could I be pregnant or is it just the affect of the morning after pill?