I lost alot of hair on the Mirena. It is very upsetting as a woman to lose so much hair. When I took a shower I would clog the drain after shampooing and again after conditioning. I actually took what I lost in a shower to my doctor to show her how much I was losing. I would say it started coming out about 1 month after I got the Mirena and although it slowed down a considerable amount after removal (7 months ago) it's still falling out. I'm at a loss at what to do, but like you my volume is not 1/2 of what it was. I do see some regrowth which I'm thankful for, but I want it to stop falling out.
And also, my neighbor is losing her hair. She told me she's going through a battery of tests to find out why its falling out. I told her my situation with the Mirena - and her mouth dropped open. Yes, she's on the Mirena also. I'm sure that's her answer also.