Okay so this is what I was told by someone who runs a hatchery. When you sex chicks soon after they hatch the reason it's only 96% accurate is because when vent sexing your looking for a bump in the vent. Well apparently some of the inncorect sexing comes from some females who also have the bump in their vent. Thus the dominant hen. I have one myself she is the loudest rules everyone even though we have a silkie rooster she is the top of the ladder silkie roo is the bottom. She also has spurs she doesn't mount which I told is not common for a hen to mount but its not unheard of. She also lays a beautiful egg every other day.
This could also be why she looks more rooey to me.she
She could be a late bloomer as well as the days are shorter which makes a big difference and...has she gone into molt recently? If so she may have reached her point of lay and then gone into molt. My hens stopped laying in august and I got them to start up again in october by upping their protein .
Also some hens reach point of lay when the weather changes and wont lay until spring time. If this is the case its probably better for her anyways sometimes there is problems with hens who lay to soon.
I too have a almost 8 month old pullet who is squatting for me with bright red comb and wattles and has been for a few weeks and she goes into the nest box and...no eggs yet.
But I also have the silkie who was dubbed hen who just turned into a rooster at the same age. Depending on where you got your birds also makes a difference if they are hatchery stock it can take a lot longer.
I had a 29 week old Black star who didn't lay yet and they're notorious for laying early.
