A serum estradiol level of 104 pmol/l is rather low. Perhaps you weren't absorbing very well from the gel. I never did and now use Estradot which has been much better. Sounds as though the hairloss might be down to low oestrogen?
It's not so much which product is best but how well you, personally, absorb from it. I only got to 89 pmol on 3 pumps of gel and I was aiming for about 250 to help avoid osteoporosis. I didn't do much better on Sandrena. On 125 mcg Estradot I got up to about 460, so did much better on the patches and was able to drop down to 100 mcg. Maybe give it a bit of time on the Estradot and get tested again.
My own hair didn't thin dramatically when my oestrogen was low, but I do shed less these days.
Hope this helps.
JP x