Hi i had sex with a girl about three months ago. about 6-8 weeks after we had unprotected sex (condom broke and i brilliantly thought i could continue riding bareback) and i withdrew my penis before ejaculating she had 3 periods in one month. shortly after hearing this i had her take a pregnancy test. it said negative. however, after a recent falling out with said girl i havent been able to ask her some personal questions. she hasnt been gaining or losing weight, no visible sign of fatigue or aching, and no vomiting. we have the same class everday for 3 hours so i can tell if she is ill or not.

basically my question is this, could the pregnancy test be wrong during the 6-8th week of us having sex?