Sessions with Beth - 3 exercises that make a world of difference

Today I brought Charlie to Beth Glosten's, in Redmond, for a pilates session for me, and then a lesson on Charlie.  I have been struggling with how to try to fix a crookedness I can't feel.  Beth very patiently went through how I would describe how things feel, so that I can label them and fix them without getting confused.  For example, if I start looking in the mirror, I can see that my left leg is much longer than my right.  But my right seat feels much heavier than my left, so if I try to fix it by putting more weight in my left leg, I just make the problem worse. 
Beth identified three things for me to focus on:
1.  When going to the left at the trot, make sure my shoulders are in the direction I want Charlie to go.  I usually have to think to myself to put my right shoulder forward, and then I also turn my head, so I have to put my head back looking between his ears.
2.  Still going to the left at the trot, try to sit with my left seat bone as close to the center of the saddle as I can get it.  One way to do this is by putting my left hand under my butt so I have another way to feel where it's at.
3.  Use my core.  This is both to control my seat bone (for example, I use my core muscles to sit "softly" instead of slamming my weight down on the sitting step of the trot) and also to reduce the S curve in my spine. A side note here, I can get the lower part of the S correct, but I can't feel the upper part of the S.  I need to lean forward a bit, but not round my shoulders, and then put my head back.  So shoulders, you are on deck once I master this twisty pretzel thing in my hip.
When I first get on (or take a break), I look in the mirror, and if my left leg is long, I shorten the distance between my hip and my ribs on the left side (do a "hula").  This sounds simple, but is really hard to get those muscles to do their job.  My leg and my butt are far more willing to do the work than my core muscles.  I think the same thing trotting.
4.  Cantering right is also all about the core.  If I try to push my left sit bone towards the center using my leg, Charlie still flings out through his left side.  But if I use my core to hold my sit bone in the center, Charlie comes up balanced underneath me and stops bulging out.  It was like a miracle once I figured out the two different ways to try to move the sit bone and how differently Charlie reacted depending on which one I did.
We did 10 meter figure 8s at the walk, and then 20 meters at the trot.  Beth said the exercise without the left stirrup is a good one, but for now, I need to retrain the muscle memory so I don't panic and revert to the bad habits.  We also did 2 point, but a "correct" 2 point where I hinge at the hip, keep my leg back, and use the core in "plank" to hold me up, instead of just pushing my butt over the back of the saddle and letting my legs slip forward.
It sounds really simple, and I could feel the difference, but I just don't have very good muscle control yet to keep holding those movements.  I have my fingers crossed that with something this specific to focus on, I'll be able to see some progress by my next session with her.
Beth also had a couple other observations - she noticed my saddle is always tilting left, and since it is a Flair (with the air panels) I let some air out of the right side to try for the next ride.  The gel pad also shifts left.  She said she thinks that I am landing first on my right sit bone, and so I twist sideways to make up for it.  She thinks that I feel heavy on the right side because the sit bone is in a different place in the saddle - it rides much closer to center while the left one is way out to the left, so that is why I'm getting confused because the right leg feels strong and secure but the left one feels loose and flappy, even though it is the one bearing all the weight (proof is in the long stirrup).  She suggested also getting on from the right side instead of the left, just to make my brain have to flex a bit.
After she watched me, she could do a really good job mimicking the movement and then showing me how to change things to change the way the movement would work.  As a kinesthetic learner, this was spectacularly useful for me because I don't always get it with just words. 
She has also given me exercises (that are in her book) to work on at home to strengthen those core muscles and refine them so that I don't have to move in one giant block and can get the core working.  Right now, it is an embarrassing soft squishy marshmallow. 
I am inspired!  All is not lost and I don't have to quit riding!