Cramps no period HELP

Okay, so I'm on a birth control and I have been for about two years now. My boyfriend and I had sex December 28/29, my period came on January 10. I am now waiting for my period to come on. It was supposed to be on February 7th, no signs or symptoms of that. This now makes me 3 days late. All today I have been cramping but I haven't spotted any blood even when I use the restroom and wipe.