Ok, first off, I gotta say, I love how painterly this looks and how you mix all sorts of delightful colors together. I might darken her hip behind the hand holding the mirror, to help the hand stand out and since the light seems to be coming from an angle that would push the younger girl’s shadow that way. For the mirror, maybe use a yellower highlight on it and lighten up the background behind it so you can see it more fully (maybe there can be a washcloth hanging up behind her or something?). As for the light shape on the hand…I might have her fingers wrapping all the way around it and put some highlights on them…but I feel like that critique is out of my league lol