PLEASE HELP!

Has anyone ever gotten Pregnant after their ovulating days have pasted. I had sex on the 15 and my ovulation days were a few days before. I've taken 3 tests 2 I looked at after the 10 minute mark and were positive but negative before and then the 3rd one the next day was positive. I'm 8 days late for my period but everything I read says I can't be pregnant if I wasn't ovulating or my ovulation days weren't almost there. Could I be pregnant?