With the FT4 and FT3 levels being what they are, and with a number of symptoms, I also suggest testing for Reverse T3.
If that's what was written on your report for the TSI, I'd say there was a typo and there should have been TSH because we don't really see thyroid testing done without TSH and that's definitely the reference range used for TSH, although the actual result could very well be that of a TSI test. When you see your doctor, you might try to clarify that.
In addition, some people say that any TSI indicates Graves Disease, so if that < 89 is really a TSI result, you could have Graves Disease, which is associated with hyperthyroidism.
When you have your next testing done, be sure to ask your doctor for, BOTH, the TSI test and the TSH tests along with Free T4 and Free T3. Also ask for the other tests I mentioned - the B-12, D, Ferritin and cortisol.
I did notice that I made an error in my previous post... I said: "FNA is, typically not done until a nodule reaches 1 mm..." That should have been 1 cm instead of 1 mm. I'm sorry for that mistake.
Even though the nodule is small, you'll want to follow up on the ultrasound, as well. A solid nodule (not calcification as indicated by your chiropractor) needs to be looked into because solid nodules are more likely to indicate cancer. Ectopic tissue is tissue located someplace other than where it belongs, so they'll also want to follow up and see if the other lobe of your thyroid grew into a position in which it doesn't belong. This could cause issues as well. I'd suggest the nuclear follow-up as recommended on the ultrasound.
At this time, IMO, more testing is in order before pills would be needed because your thyroid hormone levels are still acceptable.
Please check the Thyroid Stimulating Immunoglobulin and make sure that's what it is. The reference range looks like what we, typically see for TSH (Thyroid Stimulating Hormone), not for TSI. Also, please verify that result.
Your other thyroid hormone levels are not horrible... Your Free T4 is at 70% of its range, which is higher than most of us, typically, need to have it, indicating that your thyroid is producing adequately. You Free T3 is at 53% of its range, which is slightly below what most of us need... Free T3 should be higher in its range than Free T4 in its. Your Free T3 level indicates that you might not be converting the Free T4 storage hormone to the usable Free T3.
Weight gain is, typically, seen with hypothyroidism, while hand tremors and eye lid twitches would most likely be seen with hyperthyroidism, if they're thyroid related. The other symptoms (fatigue, anxiety, joint pain, gastro issues) can be related to either hypo or hyper.
The antibody tests (Thyroid Peroxidase Antibodies (TPOab) and Thyroglobulin Antibodies (TgAb) indicate that you don't have Hashimoto's but some people have been diagnosed with Hashimoto's, based on characteristics of the thyroid as seen on ultrasound. Nodules are common with, both, Hashimoto's and Graves Disease.
Thyroid Stimulating Immunoglobulin is the definitive test for Graves Disease, but the result and reference range you have listed don't really match what we, typically see, so once you've verified that result and the reference range, I'll be able to better assess that. However, your actual hormone results don't really indicate hyperthyroidism, so I'd say Graves isn't probably a diagnosis, but we never say never... :-)
The ultrasound indicates that you're missing a thyroid lobe, which is pretty rare, but not unheard of. You do have the nodule - 5 mm is quite small and FNA is, typically not done until a nodule reaches 1 mm unless there's definite cause to believe there's cancer. Less than 5% of all thyroid nodules are cancer and here's no recommendation for FNA follow-up in the report.
Have you had any other blood work done, such as for Vitamin B-12, Vitamin D, Ferritin, cortisol, etc? Vitamin B-12 deficiency can cause horrible fatigue - even worse than that caused by hypothyroidism. Vitamin B-12 and D are needed for proper metabolism of thyroid hormones. Ferritin is the iron storage hormone. Iron is needed for proper conversion of Free T4 to Free T3, plus iron deficiency can also cause fatigue.
Cortisol is an adrenal hormone excreted when we're under stress. Excess cortisol can cause weight gain and other symptoms.
If you've had any other tests done, please list the tests, their results and reference ranges.