What strikes me most about your post is how intellectually honest it is, and also how exhausting it sounds. You're not looking for permission to relax - you're looking for permission to stop analyzing the situation, and I'm not sure analysis will get you there.
You talk about the relief being lost in shipping, and I wonder if part of you is waiting for it to arrive so you can finally feel like the decision was correct. But relief might not be the right metric. Some big life changes don't feel relieving; they feel disorienting first and clarifying later. Those are actually often the ones that stick.
The scoreboard in your head is interesting to me because scoreboards measure performance against standards that aren't yours. You can try to ignore a scoreboard, but the only way to stop being bothered by it is to actually stop believing in the game it's measuring. Full clarity on that usually takes longer than a month.
Here's what I'd watch for: Are you grieving? Because leaving a twelve-year identity - even one that stopped fitting - is real loss. The salary, the title, the structure, the people, the daily problem-solving - that's all gone now, and loss requires mourning before it requires meaning-making.
So maybe the real question isn't 'why do I feel nothing' but 'what would I need to feel?' Is it accomplishment? Growth? Impact? Autonomy? Connection? Once you name what you're actually hungry for, the work piece becomes easier to design around. You might not need to escape work - you just need to escape the specific work that starved whatever part of you was quietly rebelling.