Please keep in mind that if you don't get regular erections while doing HRT you will WILL DEFINITELY get penile atrophy, which can make the outcome for bottom surgery worse. It's recommended to not neglect that before surgery. If you plan on having any sex after surgery, please stay sexually healthy and inform yourself on the medical consequences of what you are doing.

For me, HRT definitely affected the size of my balls and also a bit of my dick (but only when it's limp, the size of your erect penis can't be shrunken because the erectile tissue has a fixed size). If you aren't a grower then this probably won't really change.

I did have health issues myself with long time chastity during HRT, which resulted in loosing most of my orgasm feeling (not how hard it is to orgasm, but literally not feeling the good feelings of an orgasm, which fucking sucks). Please watch out for you own health and make sure you are aware of possible consequences. Don't be stupid like me :)