I am surprised to see no Free T4 test. You should make sure you are always tested for both Free T4 and Free T3, the biologically active thyroid hormone, each time you go in for tests.
Your TSH level only indicates that you don't have primary hypothyroidism. There are many other causes for inadequate tissue thyroid levels that result in hypothyroid symptoms. If your Total T4 is indicative of your Free T4, then that would be much too low in a reference range that is far too broad, due to the erroneous assumptions used to establish the range. Your Free T3 is at 37% of its range. When you consider your TT4 and the FT3 I expect that your Free T4 is way too low and your body is converting T4 to T3 as best possible in an effort to maintain thyroid function as well as possible. Many of us have found that Free T4 should be at least mid-range, and Free T3 n the upper half of its range, and adjusted from there as needed to relieve hypo symptoms.
I see as a good thing that you are seeing a doctor that is apparently willing to treat you clinically, for symptoms, rather than just by test results compared to flawed reference ranges. I do not think that 1/2 grain of Nature-Throid is anywhere near the amount you are going to ultimately need. That is so conservative a starting dose that if you don't push to go back every 4-5 weeks for re-test and a med increase, it will take a long time to reach adequate levels of Free T4 and Free T3.
Understand that the 1/2 grain is not going to make much, if any, difference in your Free T4 and Free T3 levels. That is because serum thyroid levels are the sum of both natural thyroid hormone and thyroid med. As you start on the med, your TSH will drop and accordingly the output of natural thyroid hormone will be diminished. Only when TSH is suppressed enough to no longer stimulate natural thyroid hormone production will serum thyroid levels reflect further increases in thyroid medication.
Since hypo patients are so frequently deficient in Vitamin
D, B12 and ferritin, you ned to get those tested and then supplement as needed to optimize. D should be at least 50 ng/mL, B12 in the upper end of its range, and ferritin should be at least 100.
If you don't mind, please post the saliva test results and reference ranges shown on the lab report.
Another possibility that occurred to me, because of you mentioning light sensitivity and salt cravings, is the possibility of low cortisol. If that is the case you would need to address that even before the thyroid issue. So, if at all possible, you should get the 4 tests I mentioned above: Free T4, Free T3, Reverse T3, and cortisol. The best test for cortisol is a diurnal saliva serum cortisol (free cortisol) panel of 4 tests from different times of day. Doctors usually won't order that and only will order a morning serum cortisol (total cortisol) test, which is not nearly as revealing, but better than nothing.
Well, assuming you have made no other changes, it could be related to the NatureThroid. If so, it should pass soon as you body will accommodate. .
What symptoms do you have besides lack of energy? When were those test results from? When did you start on the Nature-Throid? No test for Free T4?