Thanks for the replies, everyone. I was hoping with the big tail early on, it would be a she. The tail was always big, whereas the Big Boy's tail still hasn't started growing. So confusing!
I'm really worried that out of 24 eggs, and 9 surviving chicks (first time hatch), that we might only have 3 hens.
Of the 3 Light Sussex, One is clearly male, one is clearly female, and this one is a wonder. VERY WELL developed - always big an "motherly" since the beginning. Her name is...