Please post the reference ranges on your TT3 and TT4. FT3 and FT4 are better tests.
How much Armour are you taking?
Do you have any hyper symptoms?
I really do need to know the reference ranges for your TT3, TT4 and FT4. I have to be able to see where in the ranges you fall. Reference ranges are on your lab report and are often in parentheses. FT4 range, for example, should be something like (0.8-1.8).
Cutting your meds in half is pretty drastic.
Heart palps can be from both over- or under-medication.
Thyroid meds don't lower antibodies. Most likely what's happening is that your thyroid is functionally dead, so the antibodies are going into remission. You had a very high antibody count five years ago. The antibodies have done their job and destroyed your thyroid.
If you're just feeling a little hyper, you might want to reduce your meds a little, but I think cutting them in half is too drastic.
You still haven't given me the reference ranges for any of your tests, but TT3 and TT4 in your original post both look on the low (hypo) side to me. Is your doctor wanting to lower your meds based on symptoms? What is his rationale for such a huge reduction?
I think 90 is a more reasonable dose; you could even try 105.
It is hard to find a good thyroid doctor. Look at the advances that have been made in diabetes testing and treatment while virtually nothing has changed for thyroid in 50 years.
My endo and I both think my thyroid is dead; and that was pretty much confirmed by my last ultrasound since my thyroid is now atrophied. I take 88 mcg of T4. 120 mg of Armour is roughly equivalent to 146 mcg of T4, so it's possible that's a full replacement dose for you.