Hi... What's your actual Free T4 level and its corresponding reference range?
Also, what medication and dosage are you taking and how long have you been on the same medication/dosage? On the day you had the blood work done, did you take your medication prior to the blood draw?
What medication and dosage were you taking prior to coming down with mono? Did you feel well on that dosage?
Have you had any cortisol testing done? It's possible that your symptoms are related more to adrenal issues or to the EBV than to your thyroid. Too much cortisol can cause weight issues.
Also, have you been tested for vitamins B-12 and D and Ferritin? All of these are necessary for the proper metabolism of thyroid hormones, plus Vitamin B-12 deficiency causes horrible fatigue/tiredness, as well as inability to get restful sleep.
Have you been tested for insulin resistance? Insulin is necessary for metabolizing sugar/carbs we eat. If we eat too much carbs, we spike insulin, which is known as the "fat storage" hormone... the body turns food into glucose (sugar), which insulin shuttles into fat cells if it's not used for immediate energy. This can appear to be slower metabolism. Insulin resistance is often/usually a forerunner to type II Diabetes. Fasting blood glucose and and A1c test can help determine insulin resistance status.
In addition, too much thyroid hormones (if both FT4 and FT3 are into upper end ranges) can cause tiredness/insomnia, vision issues, etc).
I'm sorry to ask so many questions, but these are all things that can interfere with
Have you ever had the TgAb tested? That's the other antibody test for Hashimoto's... if you've never had that tested you could still have Hashimoto's and there are some people who are diagnosed with Hashimoto's without antibodies at all based on thyroid characteristics shown on ultrasound. Have you ever had a thyroid ultrasound?
TSH is affected by many variables other than thyroid hormones; it can fluctuate by as much as 70-75% over the course, of a single day, which is why it shouldn't be used to determine hormone dosages.
There isn't a real big difference between 3/4 grain and 1 grain. Have you tried any other medications, such as NatureThroid, NP, etc or even T4 medications with added T3, etc. There is a variety of medications you could try that might work better than Armour.
Are you getting the thyroid tests done at the same time of day each time? Also are you waiting 4-6 week between dosage changes before you have new tests done as it takes at least 4-6 weeks for Free T4 levels to stabilize after a dosage change; therefore testing sooner than that won't give you accurate measurements.
And yes, EBV could also be affecting results, as could Hashimoto's, since it appears you've never had TgAb tested.
An ultrasound several years ago would not be valid now as things change over time. That said, did that ultrasound indicate nodules or any other specific characteristics?
It's important to note that elevated reading of Free T4 and Free T3 indicate over-medication and as noted above, some symptoms apply to both, over and under medication, such as tiredness, insomnia and vision issues.