My boyfriend and I had unprotected sex on April 11 n 12(my most fertile days) I didn't take plan b until the 13. I had a slight headache the next morning, but nothing more. It is now the 21st my period isn't due until the 25 and I have been having severe cramps for 3 days now?! I never bled or anything, I usually don't cramp until the day of. I get pregnant very easily n I am extremely tired all the time, for no reason. I know plan b only prevents ovulation. Can I still be pregnant, please help.