I have no advice but stopped over a month ago for a similar reason, I just couldn't handle the progesterone I had to take 12 days. Testing showed my E and P to be very high on hrt anyway even on a very low dose so not a bad thing I stopped.
I ended up paying to see a psychiatrist privately, tapered off one anti depressant and have started another and that seems to be going in the right direction.
I know the flatness you describe too, that could be related to a normal dip in E if you have just started a bleed which, BTW, is totally normal if you've just changed or stopped hrt.
Do you want to find an alternative hrt you can tolerate? Hopefully someone om here can advise you re that.