Humble pie eating contest

We are racing out the door to White Pass, so this is a very brief synopsis of my lesson - which is fine because it's not the sort I could pleasantly dwell on. I'm going to tell myself that breakthroughs to the next level don't happen until you're really struggling, although I'm not sure that's true, but I WAS struggling today. We went back a few lessons to leg yielding. To one direction (the right) it's a cakewalk. The other way (left), I get myself all tangled up, we start going sideways and eventually just halt. There's a lot going wrong. My right hand lifts up and then opens - my right leg squeezes up to the saddle pad, my left hand starts pulling, and my legs are kicking inconsistently. We had to break it down into a walk, then with Shannon walking alongside me with each specific instruction, and finally, with her riding and me watching. First - I need to give the leg aid when his hind leg is lifting. So if we're going right, it is when his left hind leg lifts, which is when my right hip starts to move forward. My leg sputters. Second - My leg aid isn't correct. I either twist my toe out to dig my heel in, or lift my heel up to squeeze way up high next to the saddle pad. This was easiest to see standing on the ground watching Shannon give the aid. She squeezes from the lower leg but doesn't really use her heel at all. This part, oddly, was absolutely the hardest for me to wrap my tiny brain around. Third - I get frustrated and then start spazzing out with my hands and legs. Fourth - So Charlie stops listening because it's information overload, and then, on the rare occasion when I get it right, he doesn't respond, so I don't realize whether or not I've gotten it right. (Until Shannon gets on, gets him responsive, and then I get on again.) I'm having a low moment where I feel like there's no way I should be competing or even wasting instructor's time, and then I repeat to myself that this is just the next layer of refinement, and it feels overwhelming because it's all so new, but just like struggling to keep my leg from swinging two years ago is now just habit, one day this will be too and I'll be working on something even more refined and feeling just as frustrated about how I'm the worst rider in the world. In other words, I'm trying to put a positive spin on this (It's progress!) instead of a negative (I suck!).