Smaller Eggs than I was expecting

[jvp0719]

I have RIRs and they have been laying for about 4 months now. The eggs are smaller than I was expecting. They barely reach 2 oz; sometimes they don't. Could this be a vitamin/mineral deficiency? They are fed Organic Layer free choice as well as Oyster Shell, Free-choice. They also get our Organic Vegetable scraps daily. Fresh water a few time a day, but always water available. Their coop and run gets moved weekly to new grass.

Any thoughts?

Thanks