We got five chocolate orpingtons this year. While they have all gone through stages where I was *sure* one or two was a rooster, at 6 months now they are all pullets. Also, we have three different comb/wattle sizes in those five chocolate orpingtons. Even our three new lavender orpingtons each have a different height/shape comb.
I'd not make a judgment call yet. Your second photo looks just like our Fudge (in front) and Pudding (in back left). Both are laying eggs, so definitely female.
All the solid chickens in this photo are orpingtons. Aside from the buff orpington, when this photo was taken all the orpingtons were 4 months old. All are female. As you can see in the back right lavender, Marigold has quite a large comb/wattles. Currently Fudge the chocolate orpington has the same size comb at 6 months.
Your bird could still be a cockerel, I'm just letting you know our orpingtons developed at different times and still have different sized combs.
(Note, hardware cloth has been screwed in, this was during coop remodel.)
I agree, this is a wait and see for me. The comb and wattles are very red, but I don't see any other signs of a cockerel. At 12 weeks (3 months) you're right at the beginning of the age when male specific feathers start to come in.
Thanks for all your informative answers! Yesterday the chicken in question was asking for attention- and when I went to pick her up she very much squatted! So I am thinking it's a girl! But now I have a new question - Should I get my lay boxes set up? They are currently blocked off. I thought Orpingtons started later. Is 16 weeks old possible to start laying?
Squatting is a great sign she's a girl! I would set up the nest boxes. 16 weeks is a bit early for her to start laying but as long as no one is trying to sleep in the nest boxes it's ok. I have 2 chocolate orpingtons and one started laying at 18 weeks and the other (that is much larger and still hasn't got much red) STILL isn't laying at 22 weeks.