LOL i didn't grow that much during puberty myself but i 'm surprised more ppl wouldn't buy some uniforms like a size up as long as it wasn't too baggy just in case, tho other than a chest size growing given how the "Omg i'm so fat/gained weight ;_;" chapters of some animanga when they barely gained like 3 pounds would make me think it'd still make /some/ uniforms tight even if it's not that noticeable to others lol
Although other than like going to some sponsored/associated store , you'd think if most schools had uniforms they'd provide it themselves or be able to 'adjust' it (tho i guess easier to hem something shorter versus you needing a bigger size)