"small, light, and perfect" - even though she's supposed to be 5'8".
In comic books, height is very relative. I've found descriptions listing Babs as 5'7", 5'11", and Batgirl Y1 made a big deal of how short she was, presumably placing her under five feet.
Selina may be supposed to be 5'8", but that means nothing in the world of comics.