Me and my girlfriend had protected sex on February 6. She has a regular 28 cycle and she ovulated on the 10th. I was worried because we had sex during her fertile window even thou we used protection she told me that her period came on the 24 but during I have heard of some thing called implantation bleeding and that it could be mistaken for a period but that I here that it usually happen 1 week befor her period Arrives other on her period. Could she be pregnant ??? She has no real syntoms and because it was make up sex due to time I did not finish also we used protection

Thanks