We have a couple of guys in this territory now.
Background: With adrenal fatigue/stress, more of your T4 converts to rT3 and rT3 is twisted and does not work, but can block fT3 from working. This means that one can have lower body temperatures even with apparently adequate levels of fT3. See this sticky for more thyroid info: https://forums.t-nation.com/t/thyroid-basics-explained/185344
Time release T3 is preferred because fast release is too spiky and short and multiple doses are then required. In USA, time release is only from compounding pharmacies.
When you first start taking T3, rT3 is reducing its effect. You need to find a dose that restores body temperatures without feeling jittery or over heated.
As rT3 drops, timeline unknown, then you existing dose can be overdosing and you need to find a new balance.
For T3 to work to lower rT3, you need to reduce or shutdown your TSH so there is less T4 to feed T4-->rT3. If body temperatures are low, your pituitary will probably still be releasing TSH which will then lead to T4-->rT3.
Because your doc cannot tell you what your dose should be, you have to experiment and need a lot of low dose capsules so you can make adjustments. 5mcg would be a good choice. You can dose twice a day, but might prefer once in the morning to allow your body to slow down in the evening. Or maybe two in the AM and one mid-afternoon. You need to keep a thermometer in your pocket to see whats happening.
The above is not the whole story.
Some labs higher range limits on rT3 than others that raises some questions. If you are in the upper range, there are rT3 effects going on. It is not like you need to be over the range before there are any problems. So you might need a doctor to cooperate even though rT3 and all of your other thyroid labs are "normal". Your energy levels and body temperatures are important. If you feel better, body temperatures are up and your mood and energy is better, you can can have confidence in the obvious conclusion.
I have discussed the other symptoms in the above sticky, but from a doctors point of view, they are not specific except perhaps sparse outer eyebrows. We can add the loss or diminished reflexes as something a doctor can recognize. You will probably need to advocate for your self.