They are definitely growing up! They look like they're about to hit the "ugly chick" age when there's fluff and little feathers on them at the same time. Before long they'll all be laying eggs.
From what I've seen in my chickens so far is that any cockerels will *usually* develop a comb first and I've noticed mine stand different. Almost in an assertive and watchful way.
And that is awesome that she loves you this early in her life! Hopefully that will carry on through the years.