Light cramping

This app says I'm about 3 weeks and 3 days, I tested positive in pregnancy tests but technically I'm not late yet for my period. AF is due in 3 days, but like I said I took a test and it was +.. Well I've noticed some light cramping? Is this normal? Am I gonna start my period? Or is it just something that happens this early in pregnancy? The cramps don't hurt, they're just uncomfortable I guess.