Your symptoms are like the ones I had 6 months ago. Does thyroid disease run in your family? A low TSH level means hyperthyroidism or maybe Graves Disease. Your other levels are normal. I'm not a doctor but speaking of my own experience with the racing heart - agitation - diarhea - sore neck with several nodules on the right and the left lobes Heat intolerance and a TSH level of .02. It was Hashitoxicosis. It lasts for about 6 months. At first you have symptoms of Hyperthyroidism after all the hormones have leaked out of the thyroid you become Hypothyroid which is the opposite or similar to Hashimotos. This can last approx an additional 3 months and follows by remission. The nodules will shrink during that time. However, most people that have this eventually do get one or the other thyroid problem. It all depends on how your Thyroid Antibodies. look. Have you been tested? I have been in remission for one month now and feel pretty good accept for one nodule that is still bothering me. Hope you feel better soon.
The thyroid volume is about 37 cu cm, which is about 1.5 times the upper normal size range (mainly due to nodules)
The doctor may consider the biopsy for hypoechoic nodule; you mentioned one nodule is hyperfunctioning (hot), is this biggest one? (If so, no biopsy for it needed).
I am not sure about your particular case, but the nodules in longstanding goiters are becoming “hot” causing hyperthyroidism, common for older adults (45 y.o. and older; this is not Graves disease)