xx#2xx hit the nail on the head. Cooking is for you and your friends to always have food, or try new food, or make a FEW extra gil; its not a cash cow. The money I dont spend on food from the AH is the profit for me.
Also, I'm wondering if/why you are only making sushi for profit... There are hundreds of things to make. If you're using sushi to skill up, dont. The profit margin is too narrow to break any mats. If I were you @74 (and wanted to keep skilling), I would make Pamama au Lait (http://www.ffxiah.com/item/4302/pamama-au-lait) with Adv. Support for 2-3 levels and then without support until 80. The only down side is they dont stack.