Take a look at this in Greyscale. You have done a good job of massing your dark, middle and light values into a good composition. You have also created an interesting silhouette for a strong composition.
However, you have missed an opportunity with your background. If you can alter the background into more interesting shapes and make an opportunity to lose and find edges, you will strengthen this piece a lot.
It is OK to invent semi-specific abstract shapes in a background just for the sake of the design.