I've forgotten her name, but there has this internationally famed Russian figure skater. Average height, svelte, built like a sylph and still looking like a girl in her esrly teenage in spite pushing close from her thirties.
There had rumours of pubertal retardants used by her since her adolescence to postpone her growth and thus staying at her prime. Once she retired early, her chest went from almost flat to Hentai level within a span of few months.
An another Russian tennis player had the same thing: small or average height, thin, looking younger than her age and all. She took a sabbatical and one year later, she had to undergo a breast reduction surgery to shrink down her breasts who went from a B to a GG cup after a few months, because she couldn't perform in tennis the way she used to do with the ballast of her tits.