What Causes Heavy And Prolonged Periods After Taking Depo Provera?

Went on depo provera 6wks after giving birth. One week after getting the shot I started having a period after being advised I wouldn t have one due to exclusively breastfeeding. Period is moderately heavy and bright red. Had one depo shot before getting pregnant and my period lasted 3 months from that one shot. What can I do to get this to stop? It s affecting my mood, patience and sexual relationship. Am afraid it s affecting my milk supply as well