I'm not sure if I'm following what steps you're performing, but if you're not doing it already, try grabbing the stocking foot by the heel and pulling them off that way. I lower my waders to a point around or below my knees, then reach down (bringing my leg up somewhat to meet my hand if needed), grab the bottom of the stocking foot at the heel, and then pull that leg of the wader off. I repeat with the other leg, let out an audible sigh, then commence to telling lies about how many fish I caught.