Mirena birth control

Has anyone ever got the mirena iud birth control ? Had any problems with it? I had gotten one about 2 months and my ob told me I should bleed for (a couple weeks) then wouldn't get my period anymore but that's not the case. Ever since I have had it I bled the first three weeks it stopped a week then came back for a week went away for two weeks and is back again? It's really heavy also. Tell me what you know people