Welcome to Healthcare Magic Forum
First thing to do here is do a urine pregnancy
Sometimes when the mense appear after long time/months , the flow and pain if more then usual. This is one possibility.
contraceptives, it takes a few months for the cycle to be regular, but its been over 7-8 months since you stopped the DEPO. So an examination by a gynaecologist is reuqired here, along with investigations like a pelvic ultrasound
and some blood tests.