I'm using both Nordic Lifting knee sleeves and Rehbands. The former is practically the same as the latter for half the price, I recommend trying them, erring on the smaller side.
Ahh that's tough. I know some brands go down to an XS, like these: https://www.amazon.com/Sleeves-Compression-Weightlifting-Powerlifting-CrossFit/dp/B0179JNL6O/