Hi
If you were having regular periods before starting HRT, then you're not strictly peri-menopausal according to the medical definition, though hormones do start to go awry in the late reproductive phase, as it is called - presumably in your case causing night sweats?
That being the case have you thought of the contraceptive pill? There are a couple that contain bio-identical estradiol - same as in our bodies and in the patches and gels. QLAIRA and ZOELY. They provide replacement oestrogen but suppress the cycle so you won't get these fluctuations that are causing you problems. HRT is supposed to cushion you from the dramatic falls in oestrogen that can occur in the second half/towards the end of the cycle but maybe in your case if your cycle is strong you're getting too much at mid-point?
Oestrogen should not cause foggy head - quite the opposite in fact, so maybe something else was causing that. Continuous progesterone can lead to foggy head ( which is why I only take it cyclically), and low oestrogen during peri-menopause.
Not quite clear about what you're saying about oestrogen dose, but I use a cut-down 75 mcg patch to give approx 62.5 mcg. Going from 50 mcg to 75 mcg is not a big jump per se, especially if you are still having your own cycle because oestrogen levels go way higher than this, but it is a big jump in women who are sensitive - though usually it will be in women who are late peri or post-menopause with very little of their own oestrogen.
Hope you manage to sort this!
Hurdity x