Breeds: Barred rock, Welsummer, Sicilian Buttercup, and Wyandotte My chickens are about 21 weeks old and they do not seem full size. I would guess another month for them to be full size. I read online how some are already laying eggs at this age? I checked them and they don't seem skinny. Just young. I really hope it's not to some poor diet. I do know that factory farmed chickens grow super fast and that it's so not healthy. Any idea?