Pregnant or not?

Kayla
Ok I had sex on the 12th of May expected my period on the 20th didn't come on...... Took two test on the 24th both said no. This week I've had light cramps after being at work for a while and horrible headaches. And on and off diarrhea  I stopped my pills in January and before the pills my period would come on in the beginning of the month. What's going on? Am I pregnant or is my body readjusting from the birth control pills?