Is It Normal To Have Irregular Period After Getting Depo Shots?

am i pregnant!
i had the depo shot 2 times out of a year once in jan. 2011 once in nov. 2011 my periods were heavy and long the first couple of months then were regular after a while they stopped for 2 months then will come back , i been waking up feeling nauseous and threw up 2 times for a week , i eat something i want then i cant stand to take another bite. I been feeling cramps to could i be pregnant