I think you've made the first step in solving the problem, in that you realize you can't shoot well if you make significant aiming adjustments after you reach full draw. Minor adjustments to correct the unavoidable movements that happen when coming to full draw, yes, but not major movements. For a long time, I didn't see anything wrong with my arrow ending up 8" high at full draw; I thought that was something I could correct after I came to full draw. But in my case, I couldn't.
The next step is to learn to come to full draw with your arrow on target. The best way for me was to draw the arrow and then let it down; it took the target panic aspect out of the equation and gave me confidence that I could draw the arrow without it floating off target too much. Next, learn to do it while shooting close in front of a blank bale, where there is no pressure to hit anything. Finally, transition to a real target.
I think what initially led me astray was the thought that to avoid target panic, I should focus on the mechanics of the shot during draw, and not worry about aiming. This is still true, and I try to focus on the mechanics of the draw with every shot. However, just by making a controlled draw without focusing on aiming, your arrow should pretty much be on target when you come to full draw. If your arrow floats 8" above the target during your draw, then something else is going on.
I think the best technique is to be aware of the target, so your arrow ends up where it should at full draw, even though you are focusing on the mechanics of the draw, and then actually focus your attention on your mark after you reach full draw to make any fine-tuning adjustments that are needed, which are ordinarily so small that I couldn't tell you how much, if any, I moved the arrow to make them.