Frustrated!

Carole • 🌸💕
Okay so, I had sex 4 days before my period. Unprotected. Our first time trying. My period is now 3 days late & I'm having AWFUL cramps. They come in waves & get really intense. But not even a single drop of blood. 
​Does anyone know what could be causing this? Should I go get checked out or just wait it out?