I’m going to give more of an answer than you probably wanted, so the TLDR is that there is a correlation with T, but my T was never below the safe female range.

I was going to quote my labs from 2 months ago, but then I remembered I just had new ones done a few days ago.

In December my T was at 0.6 nmol/L (17.31 ng/dL).
In February, my T is at 16.97 nmol/L (489.45 ng/dL).

My estradiol has plummeted from 1200 to 270, with no change in regimen, but it’s not below the ideal range so I won’t consider it relevant here.

The change between these tests is that I was taken off CPA and put on 100mg Progesterone with the assurance that T suppression would be similar, but that I may require an increase to 200mg to stay in female range. I was directed to take it orally, but I’m well aware of the popularity of rectal administration and its benefits. I gave that a try when it became clear that progesterone’s metabolites don’t agree with me. I struggled with this method and returned to oral. My doctor said it should be fine, after all.

Regarding my POTS/CFS/dysautonomia or whatever is the right term for the new hell in which I live, I did notice that my days were getting physically easier in recent weeks. Hardly back to peak physical performance, but better. Mentally, it’s the worst I’ve felt since starting HRT at the beginning of 2025. I had actually been saying for a while that this feels like a testosterone–flavoured depression. Looks like I may have been right.

The moral of the story is that mental health is more important to me than physical health. I’m going back to the less awful regimen, and will trust my endocrinologist slightly less now.