The slim fit OCBD is in fact slimmer and doesn't have the box pleat in the back. I happen to have both the regular and slim fit versions. I bought the regular version before the webstore launched and had the same issue as you, perfect fit expect for the blousiness around the midsection. I later picked up the slim fit version on the webstore and the fit is spot on. Slightly tighter around the shoulders and chest but not a big deal and no blousiness.