ok i think it sounds fun to me. just a few things off the back of my head:

estimate the number of people downwards on the number line because people don't always eat that much. alternatively, get your parents to cook less.

mobilise your birthday crew, (but then not say like child labour exploitation la). simple things like toilet directions for your guests would help, etc.

expect that the colour pens will be lost lah...etc. the walaoeh part of the fun.

don't need too ganchiong. it's your birthday mah. enjoyable event :)

haha i will be at the party in moral support ok.