Aunt Flow or

For the past three months for about a few days I have had a brownish discharge following with light cramping; i am not on birth control anymore (was on the DEPO)and the last time I got the shot was in June of 2015. Ever since I got the shot though I stopped getting my period which is usually pretty heavy and a dark red. I was just wondering if this is the start of my period coming back but it's just irregular at the moment?