Pregnancy period

Has anyone here ever found out they where pregnant but still got there periods?? My boyfriend and I have had sex all throughout November and about 2 weeks before december my breast started feeling sore to touch chest pains on and off dizziness probably from working to hard and random nausea but its maybe once a week that I feel the nausea. My periods are vary irregular sometimes they are vary late late or a week early. I was supposed to start my period on the 9th od December but it started on the 3rd instead. My breast still feel tender but now my boyfriend is the one with nausea and upset stomach almost daily since the last week of November. I've taken 2 tests and they have came back negative. Could it be it's just me or do I need to see a doctor because my body is messed up. Anyone ever go through something like this or heard of it?? I could use some feed back. Thanks in advance