This might be the most important sentence in your post OP. Do you eat fast food because you don't like to cook from scratch? Or is it lack of time and, if so, could you change that in the run up to surgery? Cooking from scratch takes no more (or not much more) time than ordering and picking up a fast food meal for all, and you can make/adjust all the twiddly bits on the side that make it good for every member of your family. I live with 3 fussy eaters and I work really long hours and yet we can sit down to a meal every evening that has been made from fresh things. That's not to blow my own trumpet - I'm really lazy, LOL. I just have a stock of dinners that I can do quickly and that I can add veg, carbs, protein etc. to as we need it. Now that I'm 10 months post sleeve I just eat smaller quantities and in a different order than the rest of the family.
I will eat a ragu but no pasta (family eats all); fish pie without the potato topping; roast chicken/beef/pork/lamb dinner but just meat and a little veg; even bruschetta without the bread; curry no rice, LOL. Etc.!!! Oh and soup is your friend - you do it with bread for your family, none for you.
Honestly it's not hard after you get used to it. I wish you the best for your journey.