Ummmmm.. shouldn't your question be about breast development for transwomen? And, ya know, not about dudes getting titties?
Hormones are amazing things. Growing breasts is just one of the changes. Ya skin is going to be amazing.
ETA: if you are not on HRT, I suspect implants are in your future. Unless you develope gynomastia.
Mind me asking why you don't want HRT?
You might also post in Ask A Transperson. The Transwomen there might have some information/advice for you.