@coral Hi, Coral.
That was my experience too with the Mylan patches. They had to keep increasing the dose and I still never hit my "target" level of estradiol, so development was very slow. My Endo said that testosterone is a much more powerful hormone, so even a little can compete with estrogens.
Eventually, she took me off Spiro and had me taking Eligard (injection every three months) and Casodex tablets. I wonder if that might work for you. I have no idea what the cost might be. It could be prohibitively expensive.
The Eligard blocks testosterone production and the Casodex blocks testosterone receptors. That way if any estradiol gets converted to testosterone it will have no effect. The combination of the two is equivalent to a "chemical castration" which keeps T levels at their minimum.