Period 2 months late

Hi, I'm kinda new. My period is almost two months late. Last time I had it was November 12 and shortly after it came back on for a few days then went back off. I don't take birth control. I've have sex a few times last month. But now I'm cramping in my uterus and my lower abominen. It feels like my period is trying to come on but it's been doing it for a solid week and a half. Also, I've took a pregnancy test which came out negative. Anybody else have a similar experience?