Dosing question: would appreciate input on this

I am curious if anyone else has experienced the same thing:

For a year and a half, I took 6 grains of Thyroid-S daily and felt great on it. Neither over-nor under medicated. This is what my labs looked like in August 2016:

TSH 0.01 (0.35-4.5)

FT4 0.9 ng/dL (ref 0.7-1.5)

FT3 2.9 pg/mL (ref 1.7-3.7)

FT4 levels on the low side, which is often the case when on NDT and supposedly does not matter if FT3 levels are optimal. Since I always wait 24 hours after taking NDT before going to the lab I could assume FT3 levels were about 20% higher on the previous day, so +/- 3.48. In other words: optimal FT3 levels, and that's how I felt. I was sure I had found my optimal dose of NDT, and was happy I had found an alternative available at a fraction of the cost of Erfa.

Then, in August this year, I went to another lab with different reference ranges...this is what my levels looked like two and a half months ago, on the same dose of Thyroid-S as last year:

TSH <0.01 (0.3-4.5)

FT4 18.76 pmol/L (ref 9.03-23.22)

FT3 8.48 pmol/L (ref 3.23-6.47)

So FT3 levels seriously out of range and FT4 levels above midrange...although I did not really feel hyper despite this, I decided to cut back from 6 to 5 grains daily. That was in early August, and I had new labs a week ago, so after almost three months on the new, lower dose of Thyroid-S. This is what my labs look like now:

TSH 0.01 (0.35-4.5)

FT4 1.2 ng/dL (0.7-1.5) so higher than on 6 grains a year ago (same lab so same ref ranges)

FT3 3.6 pg/mL (1.7-3.7) higher than on 6 grains a year ago

If FT3 levels were ca 20% higher on the following day, that means they were +/- 4.3 which is out of range. FT4 levels remain slightly above midrange despite going from 6 to 5 grains daily.

I have been considering lowering my dose further (to 4.5 grains daily)...the problem is that I am currently struggling with menopause so I have no idea what is causing profuse sweating both night and day.

What I am wondering is if anyone else has had to decrease NDT from a dose on which you previously felt good for a long period of time, and go down a grain or more...?

I know we supposedly need less thyroid hormone as we age, although I would not have expected it to happen so suddenly and drastically...