I didn't read all the responses, but I can say this about my own personal experience. First let me say that I love my chick stick. Im still at 31 years old quite fascinated by it. I am able to control my erections on hrt in the following way. I no longer get for the most part, spontaneous erections, Ie morning wood; I get them when I get aroused. However, being aroused after 31 months on hrt is different. When I was a t driven person, I could achieve an erection very easily. Now with a E driven body, I require the same stimulation as a cis woman, foreplay foreplay foreplay!! If I have a typical session of foreplay before sex, ie; kissing, touching, oral, I can still have a very good erection, if those things don't happen, the only time I can get one is when I am pleasing myself. Also, Anal stimulation always produces something rock hard as well.
just try different things, women have blood flow to their privates as well, blood doesn't stop flowing to your penis simply because you take hrt.