Posing her in a different direction and moving your location would maybe have helped to give this better lighting. You seem to be off a touch on your focus. Looks like a fun time.
TC
The lighting looks way too overprocessed to me. Its clear that since teh sun was behind her you had to dodge her alot to get the detail, but because we expect shaddows there and instead get BRIGHT color it looks very unnatural when playing in the park is a more natural thing to do....i dont knot if that makes sense but I would have liked to see this from the other side where the sun was on her or something
The aperture you have chosen has allowed the background to remain 'almost' in focus which is a little distracting. Using a wide open aperture would have given your main subject seperation from the background