What are you seeing that makes you think she is a cockerel? The solid white ones won't usually get the red patches on the wings, so really the comb is the only clue until they are old enough to get saddle feathers.
Can you post some pictures of Hedwig? Try to get a good shot of her comb.
Here long tail, it is bigger then all the rests, she is so pretty! (or he), and Hedwig bosses everyone around (sorta), s/he fights a little bit, but not like my buff orps. But if s/he dustbathes, so does everyone else, ect.. She is the first one in or out of the coop most of the time... I'll try and post some in a bit, I can't go outside right now, I have to do school (I'm homeschooled)..