This is lovely. Nice expression to this young lady, nice skin tones.
One question - is the contrast correct or has the paint dried and the contrast been lessened by sinking in?
A minor issue: check that sleeve on her right (our left) arm. Try an experiment: cover that edge and notice how your eye relaxes. That sharp edge draws too much attention and looks flat, not rounded.
I'm sure the family for whom you painted this will be very happy.
The simplicity and directness of this portrait appeals to me. I think you have handled the slightly turned position of her body very well. I agree with Julie's point about the sleeve. Otherwise, I wouldn't touch it.