I agree with most of the theory you expressed and the advice given......keep working on the body position.
BUT.........
A fully developed slalom acceleration lean is a very powerful, relatively fragile and courageously challenging thing to developed. With all the body position in the world, you can be significantly hindered if the ski/binding system is not tuned properly to allow you to stably and confidently get there. Even worse, you may be fighting inherent instabilities and/or forces which you have no possible chance of overcoming without an equipment adjustment. I'm not saying that is your problem.....yet if you cannot go out there and with full concentration rocket yourself across the wake then something is wrong. It is the key skill to slalom progression. Without it nothing else matters. So keep working on it. It's either your fear, your ski causing/adding to your fear, or your position. If you study the position and are dedicated to get there but can't....then somethings amiss.
I have no idea what to tell you to do.....but safely experiment by doing something. Either that or just throw away another 1/2 season with marginal improvement. For when you are able to learn to accelerate, at will, as required to run the next pass, then it won't be too long until you run the next pass.
Change something, anything and if necessary, everything. Just be safe.
John M