I am having my wedding catered (Buffet Style for 105 people, including children). The caterer says each full tray of food will feed 12-15 people. We are having chicken, beef, eggplant parm, roasted potatoes, a pasta, and bread. How many trays total will I need of each? Do I calculate per item or just an overall average of all the food? (We are also doing appetizers during cocktail hour and a first course of a Cesar salad). I know some people will take a little bit of everything, and some won't.