I'm interested in your comment "But whenever you take a high dose of B vitamins, you'll also need a B-complex too."
I take high dose B12 for autoimmune pernicious anaemia. When I started Voost effervescent containing all the B vitamins, vitamin C and E...wow~! I felt happier, had more energy and my greenish tinge to my skin (found out the greenish tinge is seen with hypochromic anaemia and one cause is vitamin B6 deficiency) went away and I just looked better. I clearly had other B deficiencies! Probably low in vitamin C and E as well.
My ex neighbour came over was gobsmacked at how much better I looked. I figured it was down to not eating a lot either and maybe not be absorbing nutrients properly but was interested in your comment. I can't find anything about one high level of one B affecting another.
Get tested for Celiac Disease! You are at increased risk. The blood tests and genetic tests are fairly simple these days. Don't listen to doctors who think that everyone with Celiac disease has diarrhea - constipation is also common in adults with Celiac disease. Sometimes there are no gut symptoms, but neurologic ones only, including various issues as brain fog, depression, carpal tunnel syndrome, and more. If you test negative, give a gluten free diet a try anyway, since a non-Celiac gluten sensitivity is also common, and most functional neurologists say that a gluten free diet is essential with Hashimoto's.
There are good books out there that give thorough advice on healing your inflamed thyroid, including all the supplements needed to support your damaged thyroid while avoiding all iodine supplements and foods while you give it a rest. American doctors are unaware of this important need not just to supplement the thyroid hormones, but also to decrease the autoimmune inflammation.
This includes a list of thyroid supporting supplements, progesterone hormone if you test as deficient (saliva test is best), detox supplements, IgA and IgG food allergy tests to make sure that you are not eating foods that over-tax your immune system, and supporting your gut biome with probiotics and any supplements needed to rid your gut of parasites and yeast overgrowth (stool specimen test). 20% of your active T3 is converted from T4 in your gut (but only if it is healthy).
For severe neurological symptoms and fibro pain, a hefty daily dose of vitamin B1 - 500 mg of thiamine hydrochloride three times a day - will decrease the pain dramatically in many Thyroid patients. Or you can take Benfotamine, a fat-soluble form of thiamine. But whenever you take a high dose of B vitamins, you'll also need a B-complex too.
Just look on Amazon to find books on the thyroid from authors approaching the subject from the perspective of treating the autoimmune inflammation. "Hope for Hashimoto's" is one of the simpler ones to start with, but it won't give you all the information. Treating the inflammation doesn't mean that most of us are able to stop supplementation with thyroid hormone, but you will feel so much better. It's been work to self-educate, and also somewhat easier for me since I am a registered nurse, but worth it. A year and a half ago I was sick all the time, dizzy, with muscle and neurologic pain, and feeling like I choking from the neck pressure when I'd lie down. Now there's NO pressure in my neck, and I am rarely sick, and with the B1 supplements, my pain is greatly decreased.
Respect your doctor or find a better one, and of course they will always be a part of your treatment, but see a chiropractor nutritionist or functional neurologist if you can. If a chiropractor says he/she can treat your "nutrition" with manipulation, of course something is wrong with them. A chiropractor nutritionist or functional neurologist will send you to LabCore (or somewhere) for blood tests and give you saliva and stool tests for you to send off, and create a tailored program for you. Or you can do it on your own as much as possible from the books you read - better than nothing. It seems expensive, and it is a drain for a little while, but when you are stabilized it's cheaper, and it's all a lot cheaper than a lifetime of un-wellness.
Need the ranges. But it appears that you may have an issue with converting the T4 into the usable T3.
Thus if that is true, then you will likely need to add a source of T3.
Your FT4 seems to be plenty high if not even a touch too high, your FT3 is low in the range.
Since your body's cells ONLY use the FT3, then you can see why your cells are starved for FT3 and thus you are Hypo.
No need to be afraid. Those symptoms are frequently relate to Free T3 that is too low in the range. I see that you posted the % of the range for each. Please post actual results and ranges, just to double check.
If tested for Vitamin D, B12 and ferritin, please post results and reference ranges as well.
For info, a good thyroid doctor will treat a hypo patient clinically by testing and adjusting Free T3 and Free T4 as necessary to relieve symptoms, without being constrained by resultant TSH levels. You can get some good insight into clinical treatment from this letter written by a good thyroid doctor for patients that he sometimes consults with after initial tests and evaluation. The letter is then sent to the participating doctor of the patient to help guide treatment. In the letter, please note the statement, "the ultimate criterion for dose adjustment must always be the clinical response of the patient."
http://hormonerestoration.com/files/ThyroidPMD.pdf
As for your question about NDT versus T4 plus a T3 med, either will work. Taking T3 separately does provide the opportunity to adjust independently of your T4 level.