spotting then stopping

Destiny

So I’m on depo and I go to get my next shot on September 13th and I usually start my period right before I go to get my shot. I figured I would start around September 1st. Today I started spotting and then it stopped. Now I’m having lower back pains every once in a while and I can feel cramps around my ovaries, but they don’t feel like my usual period cramps. I’m sure I’m not pregnant but I am freaking out still. Is this just my period about to start?? I know it sounds funny but after not having a period for two months you almost forget how they feel.