are you sure yours are three months??? Mine are 3 months and quite a bit bigger. If they are three months then I would say pullets if not I would guess pullets...I am not seeing the red and the roos I have seen have red comb and watts not pinkish. I also agree that you would have heard a roo crow (or attempt it by now). I had a brahma that everyone said was a roo...they were wrong. She is all girl with long pointy tail feathers.
I know the brahma is a girl. I CHECK THE DATE THE GIRL WHO GAVE ME THEM RECIEVED THE CHICKS. THEY ARE ONLY A MONTH AND A WEEK OLDanD IM 100%SURE BIG MISTAKE
I took one of my rings, and got the thread from a tarp. I tied it together. Then you belly up the bird. If it spins its a girl, if back and forth a boy. How accurate? It got a spin on all of my chickens.