I kind of agree with @alecksandrs: You could move her sister more to the right still and make it more about the Angel of Light.
One thing that I've been wanting to comment on are the legs. They're okay but they're also just hanging there, the pose being not totally dynamic. I hope you don't mind, I did a few quick, rough, ugly doodles-over to suggest some other options for some poses that might feel more dynamic, as if she's sprinting in mid-air, or flying forward with one knee up.
If you like this direction for the poses, look at lots of comic books: there are always people flying in comic books so comic book artists have practiced a lot of wonderful, strong dynamic poses for doing so. Another resource to check out: League of Legends splash screen art: Riot goes in for the very strong perspective on their splash screens, and seeing how they do it for many of those might help inspire you with your illo, which also has a really strong, dynamic perspective.
Anyhow, hope you don't mind the paint-over, and good luck!