The blood sugars you mention are already diabetic level. 120 is not hypoglycaemic. it is where blood sugars go after eating if everything is completely normal.
You do need to have your doctor take the diabetes seriously. Thyroid affects eevery system in your body and if your thyroid is out of wack I think the blood sugars could be harder to control.
Thyroid nodules are not that uncommon, I doubt they have anything to do with it.
You have hypothyroidisim, but is it Hashimoto? Hashimoto is an autoimmune disease. Autoimmune diseases like company, in groups of three. Diabetes is autoimmune based.
Your doctor says you are developing diabetes, did he mention fasting blood glucose above 125 is diabetes? I hope you are on some kind of plan to control blood sugar.
Could you be hypoglycemic? I deal with those symptoms when my sugar levels drop. Have you had to do a glucose tolerance test?