Maybe you need the low dose progesterone combined from the start?
I believe that progesterone falls away naturally before oestrogen does, just from comments on this forum, so maybe it's an imbalance that needs progesterone more than oestrogen.
I also read the body turns a lot of the oestrogen into progesterone anyway, so maybe it's what your body is doing with the oestrogen a few days into treatment that is affecting you?
Then different brands of oestrogen have different effects. For me patches made my boobs sore and that was about all they did, oestrogel works to stop night sweats and flushes unless I miss a dose, then they are back immediately which makes me think my body is clearing out that oestrogen fast.
I'm switching to tibolone currently because it doesn't have side effects at all for me, unless you count feeling stronger and more confident as a side effect!
I'd love to know the answers, it's a fascinating topic that I wish researchers found interesting.