me and my boyfriend have been together for almost a year, we've been having sex a few times everyday and have never used a condom. he hasn't been pulling out or anything for the last 6/7 months and there's been a couple times i missed my period and thought i was pregnant... i took 4 pregnancy tests myself and they came out positive but when i went to the doctors it came back negative and the next day i got my period. i've been having my periods regularly and am not pregnant. does this mean one of us is infertile?