How much of each do I need?

My wedding is for 50 people.. We are having a cocktail hour with 6 appetizers (broccoli bites, lil wienies, pizza bites, jalapeno bites, a mixed fruit platter, and a cheese & cracker platter).. For dinner we are having a pasta bar (baked pasta, and pasta salad), a nacho bar (with ground beef & turkey) and a mashed potato bar (white potato and sweet potatoes).. My question is does anyone know how to figure how much of each appetizer I need and how many pounds of the main dishes I need to make? Any help would be really appreciated!! Thanks.. Real answers please. A caterer is not an option so anyone with the smart answer of get a caterer please don't bother to answer.