I like the bright colours of the image which make it appropriate for a child and make it feel childlike and innocent. The details are are excellent from shading to the braid in her hair. You definitely get a sense of playfulness and enjoyment from the work and overall a really good triumph.
Some additions if you were to revise the piece perhaps work on the details of the outfit but I understand that it is meant to be a childlike image so only if you wanted to make it more realistic.
I also like the expression on the face and the fairy dust on her wings which I can see you really thought about.