Here's another thought while we're brainstorming.
I have always been told that perfectionists have trouble completing a project because they know it won't be perfect and it's preferable (to them) to view it as incomplete than complete and imperfect.
Don't know that to be your case but in my life I've had to consciously and forcefully push forward to the end knowing that with an inexact science (as yours sounds to be) the final product cannot be perfect. I just have to be satisfied that it's the best I got.