AlanF.
Overall, your form looks pretty good to me. One thing you might try is to open up your stance. A closed stance for a right-handed shooter is when you stand perpendicular to the target with the toes of both feet approxmately even. In your photo, your left foot appears to be at least a foot's length ahead of your right foot. An open stance is where the toes of your left foot are about even with the middle of the arch of the right foot, or possibly even farther back. If you are shooting very good groups, I would not change it. However, a more open stance will allow you greater clearance if you are wearing bulky (think winter) clothes. you can also play with turning the toes of your left foot toward the target a little.
A few other things to try include lowering your right elbow just an inch or so. It may or may not help. The other thing is to photograph yourself while at full draw from the front and the back to see if your right elbow is aimed out from your shoulder, which would indicate a lack of back tension. It is hard to tell back tension from the photo.
Mike