Thank you everyone for sharing your experience! I got the mirena out yesterday, the doctor was surprisingly supportive of it. When I went for the appointment, I spoke with the nurse first (who has a mirena) and told her about the post partum depression. She said, "oh yeah that's a side effect. Getting it out, you should feel much better." Then the doctor (a different one in the practice than who inserted it) said the same thing. He didn't discount anything I told him and he added that despite what the literature says, he feels the hormone does not just stay in the cervix and there's enough of it to cause problems in a fair number of women.
So that's step one for my recovery. Looking forward to feeling better and finding less hair all over my clothes and bathroom floor...