Help me find out what's wrong!!?!??

I got my period in December 5-8 and it was normal but for he past two weeks every time I have intercourse with my bf right in the middle of it I get really bad cramps but no bleeding it feels like period cramps and doesn't go away until I stop having intercourse and Sunday I wa suppose to have my period and it hasn't came. Every so often recently I have been getting random cramping pains. What does this mean? I know I may be to soon for a pregnancy test but I want to know if I should wait a week and see if my period comes or could this mean I have an ovarian cyst. I am 21 years old and recently had a miscarriage and I don't know what to do at this point. I just need some answers or some advice.😔