What Causes Breast Pain And Change In Appetite While On Depo Shot?

I was on Depo but my last injection was beginning of May. After stopping the neddle I had my period for a month and half straight, then I was getting my period every 2 weeks, now it's been over a month and there is still no sign of it coming. My breast hurt, I'm tired, I'm moody, I'm sometimes nauseous, and my appetite has changed. I took a couple home pregnancy tests the first one was a very faint positive and the one after that was negative. Could I be pregnant or could it still be side effects from the depo shot?