Constant bleeding on birth control

When I was 15 I took the depo shot. I only did 6 months of it because it caused bleeding every single day and I didn't want that. I then got on the pill and I stayed on that until I got pregnant years later. Now my baby is 3 months old and I know I won't remember to take it everyday so I decided to try Mirena. A week after I got it, it started causing me to bleed just like the depo did. Is it normal to bleed like this on two different kinds? I was hoping it would stop my period from coming back for a while because I'm breastfeeding and I hadn't started yet. Is there a reason for the bleeding? How can I help it?