A friend of mine had the same problem and I was able to cure him in a few weeks. First there is a product called the cheater sling, it was designed for carrying your bow and to help you steady your shot. If you use it while you practice it will help. Eventually you won't have to use it anymore. Also, when you practice always start at your furthest distance and work your way in. This way you will be stronger for the shots that are harder to steady, and when you finish the days shooting at 10 yards you will walk away more confident and the next days shooting will be that much better.

Let me know how you make out.