I read your story, and it’s amazing what you do on a uni, congrats!
I always check that my saddle, it’s almost an obsession. 
Yesterday I went for a ride with the 29". I put handlebars on it and spent a long time thinking about what I was doing. Riding got much better - and enjoyable - by the end of the 20km ride. It’s not perfect, as progress takes time on one wheel. But I will work on it next time, and all my unicycles will benefit from it.
I think it boils down to a couple of factors:
- my pelvis is slightly twisted, my osteopath and physiotherapist often spend some time on that when I go see them.
- I generally use more the right side of my body and it’s exacerbated on a uni.
- I tense up in stressful situations (being overtaken by a bunch of 30 cyclists thinking they’re in the Tour de France is a pretty intense moment), resulting in more weight on the pedals and stiff core muscles.
What I worked on was relaxing more, opening up the upper part of the body (I crouch a bit, a habit from muni), shifting my pelvis to feel what happens, even in straight lines. I also worked on ever lighter pedaling. One thing that was challenging after weeks mainly on the 36" and its heavy tire is the new tire I installed which is sooooo light, especially as it’s combined with a Foss tube. But one interesting thing about it is that it’s noisy. Not noisy in the usual tire sense (sound of the thread on the tarmac), noisy like echo-ey, like the body of a musical instrument. So when I don’t pedal very smoothly, I can actually hear the crank strokes. The challenge was fun: trying to make the tire sound constant.
And the most important part was that it was fun and not frustrating.