Maybe a good time to infuse your flock with some bloodlines that are more productive egg layers - I have a line of gorgeous Isabel leghorns. I was surprised (since they are leghorns - hatched in March) -- they're just getting started, but they aren't as good at laying/production as my legbars that were hatched this spring. That said everyone's eggs are still on the small side - but usually my legbars level off around 2oz -- (size large according to USDA) Shown in the second chart on this BYC page:I hatched these guys out at the beginning of the year, like January. Definitely not short days. I can understand this would affect those hatching later in the year. Im also hoping as they approach their first year that egg size improves in the 17' season. Right now I have about the equivelent of 1.6oz eggs. Similar in size to what my Hamburg is laying and she's a slightly smaller bird. I won't hatch chicks from eggs this small so it'll be at least a full year and some change before I see what my flock can really do.
https://www.backyardchickens.com/a/charts-and-quotes
check out "how big is that egg"