Hello, I have 6 ladies that are a little over 18 weeks old. They have been on layer feed for a couple of weeks and now have a dish of oyster shells. We still have no eggs. I am a bit worried that we started them on the layer feed too early and have caused them internal damage. Oh, the breeds are 2 Barred Rocks, 2 Wyandottes, 1 Buff Orpington and 1 Blue Cochin. One more issue: I have 6 ameraucanas that are 3 weeks younger than the 6 mentioned above, and they have been on the layer feed. I would have no idea how to separate their food, so they all just eat the same thing. Are we totally screwing up our chickens by doing this? I read that pullet starter is a good all-purpose feed for all ages. Should I go back to pullet starter and supplement the big girls with oyster shell? Any advice would be most helpful. Thanks!