Dressage on Black Thursday for birds

We had a great dressage lesson today. Duke was a little stiff a couple rides ago, and pretty ok yesterday, but he got too sweaty for the level we worked. John started by holding the reins while I asked Duke to walk, and then he got Duke to go round just with his hands. I tried to watch what he was doing but it was hard to tell; I think outside hand stayed steady while inside hand used fingers only to squeeze and release. John had a couple other boarders riding, and for a while, we worked in two different 20 meter circles. He had me feel Duke bent in his body, but not in his neck, and then "plant" my outside hand so it didn't move, and use only my inside hand. If Duke tries to rise above the bit, I add more leg to push him into the contact, and then after a while, Duke was actually using his hind legs to push (and getting springy).
In the canter, John had me ride with my inside seat bone diagonal across the saddle towards his other shoulder, i.e. on the left lead, I'd slide my left seat bone towards Duke's right shoulder. This helped Duke balance or lift his shoulder or not drift out through his outside shoulder? I don't know, but it made him feel like he was a better arc around the turn.
We worked more on the 10 meter circles, and keeping him from drifting out or in, and something critical happened here - where John said when I feel "x" happening, do "y". Damn it.
When we changed directions on the 10 meter circles, John told me not to give away what has been the outside rein. So if we're going left, and we're about to turn right, don't throw away my right rein as we change directions. He says he thinks this is part of what I'm doing in the tests; that I get it almost all the way there, and then throw the reins away a little.
I was talking, and John told me to keep Duke round while he asked me questions; then he told me to keep talking while I was riding, which was impossible to do (pat head, rub belly), but it obviously did something John could see to the way Duke was moving.
John says he thinks I know the aids, I just hesitate to use them. Like I know "when this is happening, this is the correction" but then I don't trust myself to do it. He's right about that. I feel like if it isn't a disaster, it's a success, instead of asking Duke to try to be just a little rounder, just a little more forward.