If you're medicated, your TSH should be about 1.0 or slightly below. If you're as high as 2.0 or higher, you're undermedicated. How often are you checked? My endo does bloodwork every 4 months. The reason you're having symptoms is probably because you need to increase your meds.
Make sure your doctor checks your T3 level because if you're T3 is too low, it will impede weight loss. I have Hashimoto's, and after 6 years on only T4 (Levoxyl), I started having conversion problems, and now I also take T3 (Cytomel). It's the T3 level that's critical to your functioning.
As for weight loss, consider this. I, too, have lost a significant amount of weight on low carb (200 lbs over past few years). But after the first 80 lbs, I "stalled' until I lowered calories. I had to lower them again after 150 lbs. We tend to eat similar amounts, not realizing that our smaller bodies require much less food. Now I'm eating less than I ever imagined I would to maintain my 143lbs, but I'm not hungry, and my weight is stable--so that's the amount my body requires. Alas, my 'head' would like to feed me a lot more:-)