Re: Low TSH
TSH is the hormone that your pituitary gland secrete to tell your thyroid how much thyroid hormone to produce. Since you don't have a thyroid any more, all the TSH is doing at this point is giving your doctor some indication whether your thyroid medication dose is correct. Far as I know TSH doesn't have any other effect on the body.
Low to none usually means your dose was too high, though your mileage may vary. And I think for people that have had thyroid cancer doctors may like the TSH levels to be very low to discourage any lingering thyroid cancer from getting uppity. Decisions like that would be above my pay grade.
Ultimately the question is do you feel normal? Or do you have symptoms of too little or too much, both are not good. How you feel matters because it directly effects quality of life and ability to function.