Were you in a really dark place?
It can help to candle after dark, or carry the eggs into the house and candle in a closet or bathroom that has no window, with the door closed.
If you crack those eggs and look at what was inside, you will know.
Cracking the empties always makes me feel better-- I can tell there really was NO chick in there. And if I ever crack one and find a chick, I would put the others back and work to improve my candling skills. (That hasn't happened to me yet.)
It's nice to have your first broody manage things so well