Period

Hey guys the last time I had unprotected sex was in December(he didn't finish in me but I still took a plan B) 4 days later on January 2nd I got my period but then I got crazy anxious about being pregnant. I visited he gyno 2 weeks after having sex and took a pregnancy test and she told me it came or negative and said if I didn't trust it to take one again in two weeks and if it was negative that I most definitely was not pregnant. I did that and it was negative so I had protected sex this time with a condom(made sure it wasn't defective after) and then I got scared again. I'm currently on my period but I still am scared I could be pregnant? Is that crazy? Can someone reassure me that pregnant women don't have a period while pregnant (I get heavy periods and this one was no different I even stained my pants!)