This is the kind of portrait I enjoy. You have a classical pose and a beautiful model.
I think you have painted the hard part - the face- very well. My suggestions have to do with integrating the figure into the composition. There is a problem with the 'halo' around her in the background. I'd paint it out, saturating the tones of the background and also darkening them to push the figure forward. I would suggest that it makes little sense to vignette her dress when the background's baseboard is fully painted to the edges.
I'd also like to see some highlights in her hair. This will also bring her forward and draw the eye to her face. Her forearm seems a little wide, particularly at the wrist, and fingers holding the ribbon. - all easy things to fix, if you wanted to.
This is a really nice portrait. Children are hard to paint, and you have done a great job.