Okay So I Know I'm Not Pregnant I Just Had

Okay so I know I'm not pregnant I just had an ultrasound and pee test the other day and I've never had sex. My question is I'm on the Depo shot and have been for about a year I just stopped having periods with the last shot but this time when my period should be happening I feel like I have to pee all the time but can't actually pee and when I wipe there is a tiny bit of blood plus my stomach hurts is this my period.