I love playing in Photoshop. Good start on this. Suggestions: The water behind the model is to fake looking and also to high. The angle you are shooting is lower, the waterline behind her should be lower. My guess, based on the halo around her hair is that you used the extract tool to take out the original background. Personally, I would try to clean the halo up a bit, give her hairline a sharper edge. But, that is me. Now to the sunglasses. Whatever the green object is in the left lens doesn't belong in a water shot. You can either bail and just make the reflection dark, or try playing with an image "reflected". Not too obvious, but maybe something that the viewer is drawn in to examine. Remember to keep the wisp of hair reflected in the "reflection." Possibilties here are endless.
This is a four photo composite: Model, bike, arboredum, and reflection on tank of said bike.