I don't do social media either but this forum is fab for exchanging info & support.
Good that HRT was helping, great that you haven't had night sweats & you have the energy for exercise.
To answer your question re transition from NDT to synthetics, I can't convert T4-T3 very well so my T3 is always below range, but had been much better prior to peri on a 12 month NHS trial of T4-T3. The doctor who took over after the trial didn't approve of T3 use & I was taken off it & back on T4 alone. I quickly felt really unwell again, so went to a private doctor who put me on Armour. We never found the right dose, possibly because the T3:T4 ratio is high compared with human thyroid hormone production. Then the doctor who'd prescribed the Armour sadly suddenly died, coinciding with my starting the chaos of peri & as the NHS didn't support the use of NDT or T3, I had to go back on Thyroxine alone. It was only postmenopause that I saw a new private doctor who put me straight back on synthetic T4-T3 & shortly afterwards started me on HRT. So I didn't go from NDT straight to T4-T3 combi treatment.
All I would say is if your thyroid symptoms are well controlled on NDT, you're sure you're not over or under-treated on it & you have the support of a good Endocrinologist, if you're understandably nervous of upsetting the apple cart I agree, now may not be the best time to change. One thing maybe to bear in mind though, you'll know that we tend to need less thyroid replacement as we age, so if you're aware of that possibility, given over-treatment on thyroid meds can be difficult to distinguish from some meno symptoms (night sweats, flushing, palpitations, anxiety, insomnia . . .) & some of these can also occur on the wrong dose of HRT, perhaps wise to check your thyroid status with a TFT if ever you're not sure what's going on, assuming private testing is within your means.
Hope you get your blood results soon.
Wx