how can you tell if they're eating eggs

I have 3 girls 8-9 months old that we got about 5 weeks ago. (our first chickens). One laid a few eggs initially but then she started to molt. We haven't had an egg since. They seem to be in a good routine, they aren't wandering around enough to have a secret nest, we are really making sure that we have all the right food, treats, clean water, etc. etc. -- I just wondered how you can tell if someone is eating any eggs there might be?

Would you see broken shells or egg debris?

 

Only one of them is molting, and the others seem to be just losing a couple of feathers a day which I thought would be kind of normal.