Update:
I suspected four or five of my eggs to be infertile, all from one hen, so I candled them and found four (of 8) were fertile and growing. I took the others and opened them up with a screw, inside of a bag in case they exploded. All of them looked like a normal egg inside, no sign of chicks. The others are doing very well though, even one egg from the same hen. I'm glad I added those late extra eggs.
Its been busy around here with things other then eggs also. One of my four young bantams (Eve) escaped and went missing. Our cat was hungry and I was pretty sure he had gotten to her, but the next morning she was nervously waiting for me to take her in to her brothers. She was very happy to be home.
Then, tonight, while locking the chickens up, I found one of my Leghorns, seemingly dead halfway under a gate. When I got nearer, she moved, then slipped through and walked to the coop with a limp. I knew she had been attacked, but I'm not sure by what. Thankfully, the wounds were small, like it was a small animal taking advantage of her having been trapped. We cleaned up the wounds and put her in a crate in the coop for the night, so I could make sure the others wouldn't peck the wounds. Her tail was so dirty and ruined that we just trimmed the feathers off. It is near molting time, so I hope they grow back soon. This will be a good way to tell her apart though. Lol. The poor thing looks very silly without her long, elegant tail.