" I used a folded GG 1/8" pad closest to my back... [the pack] was convex both vertically and horizontally against my back"
Those pads make poor virtual frames IMO -- even when folded a couple of layers.
My sleeping pad is an air pad -- which also makes for a poor virtual frame. To remedy that, I insert a piece of blue foam (3/8" -- cut to the size of my pack back), then the folded down air pad -- then the rest of my stuff, starting with sleeping bag, clothing, etc., etc. similar to what you wrote up above. Much, much better. And the foam pad performs multiple functions as pad frame, sit pad, and wind screen.
EDIT: One other thing... do you use multiple stuff sacks... for bag, clothing, food, tent, etc? IMO, packing with stuff sacks can make the overall package "lumpy". I use only one small stuff sack to hold "misc" stuff. Otherwise, I simply shove things in, tighten up, give the pack a few good "padding down" to encourage the contents to take up slack and conform to the shape of the pack overall. My tent is packed in its own sack, but attached to the outside of my pack.