It's hard thing to deal with...the only thing I can suggest is to put several fake eggs in each nest, make sure there's plenty of bedding to avid breaks, and gather eggs frequently.
It might be a nutritional thing. Layer feed is minimal nutrition and no other foods should be given because it...
Have you found any shells left behind?
Are they good and hard or thin/soft?
Is she only eating her own eggs?
That's basically junk food, I'd pass on that.