Nice character design!
Overall looks pretty good, but I think you skimped out on the background/foreground a bit. Could'a added in some skylights or moonlight to make the art a little more interesting.

As for drawing kids/children in general, they tend to have bigger heads and different proportions compared to adults. I can't quite put my finger on it, but I think if you shortened her neck and made her head a bit bigger, she might look more childlike.