I need some help.

My boyfriend and I had unprotected sex in September. I took the plan B pill after the 72 hour period. I got my period around 2 weeks later but it wasn't t really a period. It was more of a brown discharge and was extremely light. Last month I got my period and it was almost 2 weeks late. My period usually comes around the 15 but still no period. Do you think I could be pregnant or the pill is just messing with my period.