Well, interestingly, i am in the same exact boat as you.A year ago i was experiencing hypo symptoms, got blood tests that showed only a low t3. My doctor didnt acknowledge this at all and i went several months wondering if i was going crazy. I returned to her , got the same tests done again, and this time, my t3 had decreased even more and i had antibodies that confirmed i had the autoimmune disease that attacks the thyroid. To this day, i am still trying to figure out what would have initially caused my t3 to drop, and through extensive research, i've found that there are several main reasons for this.
1-inflammation (for a lot of people, it is in the gut). Do you have any digestive issues? you don't necessarily have to have any symptoms, because infections, leaky gut, and inflammation can certainly exist without gut symptoms.
2-adrenal issues- problems with the adrenals (high levels of cortisol) suppress the conversion of t4 to t3. what is your stress level like? any chronic stress?
3-liver problems- t4 is converted to t3 in the liver, so if there is congestion or inflammation here, the liver will not be able to carry out this task.
my hallmark symptom is fatigue/no energy AT ALL/feeling like my body and limbs are heavy (amongst many other symptoms).i had very bad digestive issues which i have mostly gotten rid of through the paleo autoimmune diet). fixing any gut issues is important for addressing thyroid problems. you should really work on cleaning up your diet to an anti-inflammatory diet and see if that helps at all.
then i would take a serious look at your adrenals, liver,and blood sugar. this is of course a synopsis of what to do, but if i were you i would find an integrative or functional medicine doctor to help you through this, because i know how hard it is to do this on your own.
vitamin d is good for helping the immune system, gut health, and brain health. i was very deficient in it and now take 10,000 IU a day. it will not get rid of your hypo symptoms, ill be honest. but its just one part of the puzzle.some other things that help support thryoid conversion are selenium and zinc. you may also be deficient in b vitamins, as well as magnesium.
keep me updated on what steps you take and ill be glad to help you. any time you're feeling low about this, remember that there are others who know what its like and we're here for you.