But did you shoot the bow at 31.5" ? That will tell you more about your draw length than just hauling the string back and settling into an anchor, especially if you rake all the hide off the inside of your bow arm with the string.

I don' t change my bow' s draw length when I switch from release to fingers or vice versa. I take a shallow hook when shooting fingers, string on the pads of my finger tips just ahead of the knuckle line. When going to release, I adjust my release strap to where the trigger rests in the crease of the second knuckle. (Having it out on the tip knuckle, I tend to punch the trigger instead of drawing through it.) The length of the release head and the loop, plus anchoring the big knuckle of my index finger behind the curve of the jaw and and the knuckle of my second finger tight against my earlobe, puts the nock of the arrow in the same exact place it comes to when I shoot fingers.