I think there are a lot of muscles at work during the draw cycle, but the upper right side of the back seems to do most of the work - at least for me. I think you might be over-doing the part about rearward tension. You want to get in the "valley" of the let off, and then find the back edge of the valley - where you can feel the draw weight starting to increase just a little.

From this position, a surprise release will cause your release hand to come back across your ear - with you not even being aware of it most of the time. Staying in the middle of the valley can occasionally put you in a position where you are creeping forward and getting close to an involuntary let-down.