Birth Control Question

I had my first baby in August (her name is Naomi and she's perfect). After my 6 week check, my OBGYN and I discussed long-term birth control and he told me about Mirena, which is an IUD. I told him I'd heard horror stories, but he said those were just blown up and worst-case scenario. He said that his patients have all had great success with IUD birth control and considering I'm not sure if I want more babies, this was an ideal option for me. He answered all of my questions, gave me tons of information, and was pretty upfront about the cramping and bleeding. He told me to just give it 3 months before I decided I hate it- if it even came to that.

So I had it placed October 20. On the 28th, I got my 2nd post-partum period. And it hasn't ended. The cramps are hell. I'm constantly bleeding or at least spotting. But I want to give it the 3 months like he suggested.

I'm just wondering if anyone has a Mirena IUD and if you've had success with it. What was bleeding like for you? I really need some encouragement.