s7595, hi.
I can sympathize. I've been working on drysuit finesse myself this past week, at a lake in Oregon (elevation 2000', temps in the low '50s). I'll describe what I'm doing in case it gives you any ideas.
I put out my dive flag float, attached to a small anchor, in about forty feet of water. So I have a nice stable vertical line for reference. I can hover right next to the line, looking at its braid to see whether I'm going up or down--that's much better feedback than the one-foot increments my dive computer reports.
So first I'll descend, adding air in small increments as needed with the goal of moving down slowly (about ten feet per minute) and never having to hit the brakes nor finding myself starting back up. I try to not touch the line, just stay facing it and use it for reference.
When I'm all the way down, I'll relax with a bit of hovering off the bottom, some finning practice, some compass navigation.
Now it's time for the ascent. Again, I'm aiming for control at every moment, for never having to contort my body or fin back down. I use the line for reference but don't hold on to it (well, actually I did mostly hold on to it the first two dives).
What works for me is leaving my deflate valve turned all the way open throughout the dive, so on the way up it's venting continuously (this won't work so well if you're overweighted). I also need to help the venting along from time to time by flexing in my BC straps to move air up, flexing my vent arm up or down, pushing the manual override, that sort of thing. And this needs to happen all the way up, even in the last five feet. Actually, the amount of attention required to make a really controlled ascent surprised me.
My dive computer is set for a ten-second sampling rate. Today's two dives show ascent profiles from 40 feet as a smooth and constant six feet per minute, plus a safety stop. I'm jazzed. It didn't take that long to get this far, but it did require doing some diving with nothing else on the menu, so I could concentrate on this and note what worked and what didn't. Breath control is a huge factor, and when you're neutral (or slightly negative and finning) all the way up, you can move up or down by inches at will. It's a gas.
Good luck!
Bryan