Does Pink Vaginal Spotting While On Depo Provera Indicate Pregnancy?

i was on depo prevera since sept 2010 i was sceduled for a shot on march 7 2011 which i never got. yesterday i started spotting light pink.. it only shows up when i wipe myself. and today it seems the spotting has stopped .. can i be pregnant?? im 26 5' 5 with no medical history to report