Pregnant?

Hey guys! I’m on the depo shot for birth control and I never bleed. Every once in a great while I’ll get slight spotting. My boyfriend and I stopped using condoms recently so I’m kinda worried for no reason I think. I usually get a little crampy around the first of the month when I would normally be ovulating. I’m cramping pretty bad the last couple days and I know it’s around the first of the month but I’m scared it’s implanting pain???