One doesn't, typically, take only a T3 medication, because we need, both T4 and T3. If our thyroid were working properly, it would be making, mostly T4 and very little T3.
Your previous blood work showing Free T4 over range, but Free T3 at 5.0 was a bit more in line since your Free T3 was at 63% of its range, which is about where we'd want it, since it's recommended that Free T3 be maintained in the upper half to upper third of its range. The problem there was that Free T4 was too high... Were you still having a lot of hypo symptoms with your levels higher?
What dosage of T3 have you been prescribed? For most of us, it's best to start with a small dose (usually 5 mcg, if tolerated) and work up, as needed in small increments. The T3 can be taken first thing in the morning with your levo or because 5 mcg is a small dose, it can be taken later in the morning, since T3 is faster acting and wears off more quickly. After you've taken the T3 for a few weeks, it would be good to re-test to see what, if any, effect it's having on your blood levels. Also keep track of symptoms.
If you have to add more of the T3, in 5 mcg increments. T3 is best taken in multiple doses throughout the day, with one dose taken in the morning and the second dose taken around noon/early afternoon. This keeps levels more stable throughout the day.
If you have the results of your Vitamin D, B-12 and Ferritin tests, please post them with the reference ranges. Just because they're "in range" doesn't mean they're optimal. For instance, I find that I have to keep my B-12 level at the top of its range in order to keep symptoms of deficiency from returning. These vitamins/minerals are necessary for the proper metabolism of thyroid hormones, so if they aren't optimal, you won't get the most of your thyroid medication.
It would be much better to find a doctor who can work with you to help improve your symptoms. Selenium is essential for T4 to T3 conversion and can lower TPO antibodies. I noticed drastic improvements in my mood after eating Brazil nuts plus my TPO antibodies decreased.
T4 is converted to T3 in multiple tissues and organs especially in the liver, gut, skeletal muscle, brain and the thyroid gland.
Below is a patient with very notable conversion issues. This info is from the book "Your Thyroid Problems Solved" by Dr Sandra Cabot (I edited pages 166 and 167)...
Patient with Hashimoto's Thyroiditis:
The level of her T3 hormone is very low, whilst her T4 level is quite high; the high T4 is coming from her thyroxine medication. The body is not converting thyroxine (T4) into T3.
Free T3 = 1.1 pmol/L (2.5 - 6.0)
Free T4 = 23 pmol/L (8.0 - 22.0)
TSH = 2.0 mIU/L
Anti thyroglobulin antibodies = 80
Anti microsomal antibodies = 1200 (thyroid peroxidase antibodies)
New treatment: Patient prescribed T3 (brand name tertroxin) 20mcg three times a day, T4 100mcg a day, selenium (Dr Cabot recommends 200mcg daily), gluten and dairy free diet, bowel and liver detox.
Three months later:
Free T3 = 5.0 pmol/L (2.5 - 6.0)
Free T4 = 16 pmol/L (8.0 - 22.0)
TSH = 1.9mIU/L
Anti thyroglobulin antibodies = 40
Anti microsomal antibodies = 350
high stress either physically or emotionally can lead to high cortisol and also increase reverse T3 conversion.
Body natural response to what the brain (Pituitary) believes to be too high of thyroid level is to cause the conversion of T4 into REVERSE T3. So the high range level could reasonably be perceived to be over medicated and some of the high RT3 level as a result.
Please post your Ferritin and vitamin B12 and other levels. As stated above the B12 needs to be well up into the range in order to feel well. Ferritin is required for proper metabolism of thyroid hormone. If you are so low in Ferritin this could upset the whole apple cart.
From a directional point of view. I would agree that lower T4 medication and addition of T3 medication (staring low and working up) seems like the rational protocol given your lab results.
The ONLY way to make reverse T3 is from the conversion of T4. Thus lowering the available T4 would reduce the amount of "fuel" to be converted. it also would conceivably lower the measurement of the Pituitary to a over medication (T4) level and reduce the reaction to cause the "excess T4" into useless RT3. However at the cellular level you are still starved for sufficient FT3.
Remember that at the cellular level and to feel well, you need to have sufficient Free T3.
The statement by the Dr that T4 is the way to treat Hashi's is maddening. Treatment is not a one trick pony. True practice of medicine, and "proper treatment" is providing a method and a treatment protocol that actually solves the specific individuals problems and symptoms. Everyone is different and thus while a single protocol that "usually" works for most, does not by definition means that it works for every individual. it is amazing that Doctors don't know this.
If T4 was the ONLY thing that the body needs. Then why the heck does the natural thyroid gland produce ANYTHING other than T4? if T4 was the only thing needed, why is there even such a thing as T3 in the body? it is TOTALLY illogical.