there are better answers available on that reddit and the r/topsurgery page, but generally speaking re-growth is a myth/does not occur as the methods used remove 98+% of breast tissue (small caveat that some nipple sparing methods leave more tissue). the vast majority of people who go off/are never on t don’t experience regrowth, however some people can experience what looks like regrowth if they gain weight bc estrogen promotes fat cell growth in the chest area.
not at all! trans people, and people who are no-t, are hyper aware of any changes in the chest area bc of dysphoria but it’s not so drastic that it prevents passing or is even out of line with natural human variation in chest size due to weight/muscle tone. the best time to get top surgery is when you want it and it’s accessible for you. that’s it. + you can always discuss these concerns/goals with ur doctor.