Major hair loss (even my eyelashes have thinned out. Talk about ...

I hope you start to feel better really soon! I had my Mirena removed a few weeks ago and I started to feel better straight away. My side-effects weren't as bad as yours but were bad enough to make me a) want it out b) feel like writing and insisting that the manufacturer include 'exit surveys' in their evaluations!!! I'm sure a lot of the success is due to the fact that they can say (quite accurately) X million women around the world use Mirena. Sure they do. And the average gal would probably think "Well it can't be that bad". But what about some data about what proportions have it removed within 3, 6 or 12 months? And their reasons for removal? Anyway enough of the rant. Anyway, as far as getting back to 'your old self' goes, I've found the following very helpful:
1) increase your water intake and, if you can possibly bear it, replace sugary or caffeinated drinks with herbal teas (chamomile is very soothing, and red clover is great but tastes a bit ick!)
2) rather than thinking about having to 'hit the gym' (which may be a bit daunting and easy to put off) just try to get more active and incorporate physical things into your day. Play on the floor with your littlies, make up games than involve moving and giggling.
3) consider doing some research to see whether Mirena might have caused one or more deficiencies. I read somewhere that it can muck up your potassium and magnesium levels (which relate to your sodium and calcium levels) and deficiencies in those minerals can (surprise surprise) be associated with a lot of the side effects women have. I'm not a doctor and can't give medical advice, but I'm a well-informed consumer and I know what worked for me!
So, anyway, sorry this has turned into such an essay. I wish you all the best.