Breastfeeding women symptoms and conditions

I have hypothyroid. Have been taking Synthroid for about a year, 0.075MG a day. Had my levels checked 3 times since on the meds and still have never gotten to normal, but a lot closer. I have gained 20 pounds that I can't get rid of, which for me, is crazy. I have never had a problem dropping weight, and for the past month or so, I have started losing my hair. Not just losing it, but the texture and everything has changed. No matter what I do it looks dry and flat, and even when I condition it and also use a leave in conditioner, it still knots up and tangles. I have NEVER had a problem with tangles. It's coming out in handfuls. Im not taking any other meds, so I imagine it has to be the Synthroid. My problem is..What else can I take? I mean, I have Hypothyroid, so I can,t just leave it untreated, But I have no wish to be fat and bald either. Please...anyone know of others meds without these side effects?

I had my MIRENA put in 2 months ago. Since then, even with the holidays, I have lost 11 lbs. (bringing me to 15lbs underwt.) I have had no appetite, acid reflux, extreme nausea, esophageal spasms, diarrhea, stomach cramps, headaches, and weakness. I am also still breastfeeding, so my once fatty milk now looks like water. My husband's starting thinking it was the MIRENA, because my body must think I'm pregnant again. I am going to the MD tomorrow to talk about have it taken out.