Concerned about missed period

Deborah
Ok, so I'm hoping for comments that could help me understand what is going on with my body. Try to please not be judgmental. Here goes ... so I met someone I liked and had unprotected sex. First around Halloween and then again a few weeks ago. I got scared and took a Plan B pill the same day when it happened the first time, but that was it. I missed my period for November. Took a pregnancy test between "events" and it turned out negative. It's been 7 weeks since my last period and I'm getting very concerned about what is going on. Any helpful insight is welcomed. Has anyone experienced this before? How long did it take for your menses to return? Is there still a chance for pregnancy? I'm a bit stressed over this, sorry!