Vit. C is one of, if not the main nutrient for the adrenal glands. Improving adrenal function almost always means you are improving thyroid function as well. Adrenals help in t4>t3 conversion.
There is a giant lack of attention to adrenal function on the vwt forum.
In any case you're feeling better and that's what counts. If I were you I'd be hitting up a hundred different forms of natural C as well. Some people really do well on liposomal, maybe it means their gut is very damaged, who knows.
Some good forms of C to try are amla, all different citrus fruits, acerola cherry powder. I am a lime fiend.
Sometimes also it's just the particular source of vit. c, not that it's even an ascorbate. Some ascorbates are corn sourced, some from beets, you really don't know the sources from a label. And if it comes from chinese petroleum/ industrial waste that's a problem too. You might also try a sodium buffered ascorbate.
Vit. c is water soluble and as such should be taken multiple times through the day - something like 4x is good.
Just as an experiment you might want to try the following and see if they help you - raw egg yolks, rhodiola, licorice root, wild salmon, pantothenic acid/pantethine, royal jelly sourced cold from beekeeper.