Buff Orps tend to get nice sized red combs on hens and if they are 12 weeks old - I definately say you have all girls in those pictures. - no red at all yet, no noticable wattles, no high combs yet (but they will start blossoming on them girls soon so do not panic if in a month they all start sprouting nice reddening combs @ 16+ weeks old)
Lovely bunch you have there by the way!
Lovely bunch you have there by the way!