Sounds like you have a good set up. You can try to candle the eggs to make sure they're developing. (Do it after dark with a small, bright flashlight, so you can see better. It only takes a few seconds to look & then put back.) Once you know the eggs are good, then there's no need to disturb her more.My broody Sebright is now on day 13! She is sitting on 3 Dutch bantam eggs. I made a divider to keep the big chickens out. There is a 4" X 5" opening that she can fit thru and they don't try. She gets off the nest once a day, to eat, drink, poop, dust bathe, and preen.
I have not candled the eggs. What do you think about doing that? Will I be able to hear the chicks as they begin to hatch? I do not plan to get her baby chicks unless I think her eggs are not hatching. The thing is, Heartland's hatch day is the same as hers, and I will have one day to either get the chicks or no. The chicks days sale will be the next day. (9/30) They want me to call them the previous day if I want to reserve some Sebrights.
This is what you'll see inside the egg. The rim of flashlight should seal against the eggshell to prevent escaping light. If you have problems getting a flat flashlight against a round egg, just make an "O" with your fingers to place between the egg & the flashlight.