I think you've been a bit too generous on your shoulder measurements too. I'd go 17.5" - if you're always going to wear it with the top button undone, you can afford to have a smaller yoke to make the shirt sit nicely on the shoulders, rather than slipping off the edges.
Instead of darts, I prefer reducing the back measurements as compared to the front for the waist and chest. I don't like darts, especially in OCBDs.
I also think you should also reduce the bicep measurement to 8.25 or even 8.
Tightness in the chest can be caused by an armhole measurement which is too small.
You don't appear to have a very big chest, and yet your chest measurement is 22.25.
I'd increase the armhole measurement slightly, and make the chest 10.5" back, 10.75" front.