Custom. Im 5'8" 150, and can buy a medium at costco or a size 8 anywhere, but i have yet to have an off the rack fit me, my last drysuit was a custom, my current shop brand suit is a ladies large, which is fine for limb length, but i have too much material. Save your self esteem and go for custom. Ive had quite a few ladies of your physical description in my classes, and they end up in stock mens xl short as the rental, which is still a poor fit....