It was kinda funny how small Becky was in comparison to Baloo, or even a fair amount of similar animal characters. I guess it could be owed to her more anthropomorphic design, she'd probably look odd sized up like a regular bear similar to Baloo. I did have this funny theory of her being a runt though, her ego being owed to something of a 'Napoleon complex' similar to Col Spigot.

She does have many traits of a stereotyped fictional 'little person', 'inferiority superiority complex', irritable oversensitive demeanor, somewhat 'yappy' mannerisms.
Anyway, I think her being the mid point between Kit and Baloo is about right, maybe a little bit taller.