i am breast-feeding and pumping exclusively and i have the mirena. This is my 2nd one, I got one between my first and 2nd baby (5.5yrs). I love the mirena. I got the first one after I stopped breastfeeding (I hadn't really thought about it or considered it before that, so it wasn't because I was breastfeeding) and this one at my 6wk check-up. I bleed for a lot longer after having this one in, now bleeding with the mirena is not like a period, I use a pantyliner a day and that's sufficient, it's mostly blood when wiping, but never the less, it was like 3.5 months. With my last one, I bleed for ~2 months or less and then once it stopped my period was discharge with a pink hue that's it. It has not effected my milk supply at all (unless it increased it, which I never considered until this moment). My milk supply is WAY more with this baby, but I noticed no change once I got it.
I also notice the increase hair loss during the first 4-6months with both IUDs, it did stop and never did I see an effect in my hair. My ob says it can make your hair thicker and so you lose more, which is why you don't notice spots on your head. Good luck
PS...everyone I know that took the mini-pill, the one you have to take if you're breastfeeding, got pregnant while on it. That may be a weird thing, and I don't know that many that have used it, but the 5 women I know who took it all got pregnant while using it, so there was no way I was using that!!
Good luck!!