Shoulder-in is NOT the same thing as leg yield

If I had any pride left associated with my ability to ride, I'd have to swallow it after the humiliating lesson I had today. Ok, so first, I realized dimly that the reason that Charlie has been a bit harder to ride is because Shannon has been really busy, so I'm doing most of the riding. And so Charlie is like a living, breathing exhibit of all of my riding flaws right now. I ride crooked, I pound on his poor sides with my legs, and I scrunch up trying to get him to go. So: #1 - One forward aid. If he doesn't respond, it is the aid with the whip. No more kicking, begging, pleading. And no scrunching up my heel into his side - ride with elegant, long draped legs that have contact, but don't squeeze every stride, and definitely no heels lifting up. #2 - Watch my crooked hands. When we're going left, I should see his left eyelashes. For the right, right eyelashes. No more sloppiness on my end here! To help with this - when we're going left (counterclockwise), my right hand is the outside hand. It stays steady and I ask for the bend and flexion with my left leg and left hand, respectively. Always, I ask for collection and contact with both hands. And it is give and release, give and release. Don't forget the release. Riding on the #3 notch on the reins is about right, but my left hand opens and my right hand pulls back, so I have got to keep a careful eye on them and keep them even - in space and in the amount I pull. #3 - I let Charlie ride kind of heavy, pulling down on the forehand and bracing with his mouth. It took Shannon many, many minutes and a lot of different exercises to get him light in my hands. (The good news is, even though she had to stand there repeating herself like a broken record, eventually I did it. So I can do it - I'm not a limp rag up there completely.) This is hard for me to feel because Charlie is already so light (so pulling and bracing feel light to me), but after a few laps with him carrying himself, I was like, "oh." This took asking him to transition, spiraling in and out, and getting my hands and aids consistent. #4 - Transitions when I ask for them. Not 5 or 10 steps later. Walk to trot to walk should be CRISP! Then, I told her I was working on the 2-1 movements, but suspected I wasn't doing them right. I said the turn on the haunches felt awkward. This led to the realization that I don't know how to do shoulder-in and haunches-in. Shannon said, "Ride him in a straight line and then do haunches in" so I did, and she said "Not leg yield! Haunches in!" so I went the other way, and she said "Not leg yield! Haunches in!" and by the third try she said "Show me haunches in." So no wonder haunches in and shoulder-in have seemed so easy - I just leg yield down the long side and call it shoulder-in or haunches-in. This was great to learn (and quickly filled up my head) but excruciating. Ok, I've never been officially taught 2nd level, but why in the world would I think that the movement was just leg yield on the long side? Obviously, I can't underestimate myself. So a shoulder-in and haunches-in are his body straight, and, for haunches-in, a canter aid position leg placement. It's three tracks, but three tracks with only one part of his body moved (butt or shoulders), not his whole body at an angle like in leg yield. A shoulder-in is easier because you think about being about to ride a circle to the inside. To do a turn on the haunches, you ride straight, power-up like a piaffe, do a haunches in, then turn. So the haunches in sets him up for his hind leg to cross. Now I will re-read the dressage books and see if something "clicks". I always wondered why they said shoulder-in should be like the start of a circle and now it's clear.