One other thing... Try this test to see if you are getting a natural alignment of your shoulders to the target.

Assume your normal stance in front of a target. The further away the target is, the better, 60 yards is good. Close your eyes then draw the bow to anchor. Then open your eyes and see where your bow is actually pointed. High or low is not our concern; it's the left/right alignment we need to get right.

If your bow is pointing off to the right, move your back foot forward about 12", then repeat the test. Or, if you're pointing off to the left, move your back foot back about 12" and repeat. the test. Keep moving that back foot whichever direction you need to until the bow is in line with the target when you open your eyes. Then make sure you get your feet in that exact position every time you shoot an arrow.

The reasoning behind this is, if you do not have your shoulders naturally aligned with the target, you have to use muscle power to put the bow on target. Muscles are not very stable and can give you a lot of movement. When you align your skeletal structure to the target though, all the tension is bone to bone, much more stable, and very little muscle power is needed to put the pin on the target.