Could I be pregnant or ovulating?

I just go off Depo-Provera earlier this month. (I was supposed to get my next shot May 3) My husband and I are trying to conceive, and I have lower back pain, random sensations in my , and minor on and off cramping. Seems like early pregnancy symptoms or period about to start, but HPT came out negative and Aunt Flo hasn't arrived either. I do drank LOTS of water (my pee is almost completely clear, even first thing in the morning.) Any idea what could be going on?