I'm new to backpacking & getting ready for my first overnight. I have watched all the "how to pack your pack" videos I can find but I can't seem to load my gear so that my pack doesn't sway from side to side. I am trying to put the heaviest weight in the middle of the pack & close to my back. I was fitted for my pack at REI. I'm 5'3", have a short torso & have an XS female-specific Gregory Deva pack. I tighten all of the straps to cinch in the contents. I always have side to side movement when I walk. The weight of the pack fully loaded except for water is right at 20 lbs. Any suggestions about what else I can do? Thanks!