My boyfriend and i did not have sexual intercourse but he did ejaculate on my stomach, and we were both worried that some of his semen might went to my vaginal opening but very unlikely, but still we didn't want to take the risk so i took Plan B about 4 hours later. Fast forward about 5 days to today and i get my period, 10 days before the expected time. Is there something wrong?I have not had any symptoms (besides the normal ones from having my period). Should i be worried of pregnancy?