Maybe Slynd isn't suiting you.
There are many other options for progesterone- you're on the off-licence mini pill that can be used with HRT.
Have the drs you've seen not suggested changing?
There is micronised progesterone, the Mirena coil, patches with Norethisterone, another body-identical progesterone called Nalvee ( it's dydrogesterone) .
You really should have been advised /prescribed a different type to see if it helps not just upping the estrogen.
Are you seeing a menopause specialist privately or one at your GP practice?
From what you've posted they are not offering you any options - which they ought to. You usually try 3 months of one sort of HRT and then switch if it's not suiting.
One example which I had privately was to use only estrogen for several weeks (in peri) to establish the right dose for my symptoms, then introduce a progesterone and see if I tolerated that.
You need more expert help, I'm afraid, and you're not being offered it.
My advice is that after 4 months you need to ask to try a different progesterone.
I'm interested in why you were given Slynd as it's not a first choice unless you said you needed contraception as well and they offered it as a do-it-all.