All three of them are cockerels. Some cockerels are different then others and crow really early, and some will grow really late. They are all just not mature yet. See how light they are compared to your hens? Barred Rock roosters are light colored like that to, and BR hens are darker.
Those boys are all boys. They're just not ready to challenge your older rooster for the top dog spot yet, so they're staying quiet and keeping off the girls. They'll start crowing and mating in spring, if not sooner.
here is the first one. He looks like a rooster but I have one Dominique rooster that has already been crowing and this one hasn't. they are almost 23 weeks old.