I'm going to say roo because it is getting some coloring on the wings. Pretty bird! How old is it? My pullets have no comb color at all right now. They look a similar size.
My roos kept their round girly body for a while, too. Their combs get pretty pink quickly, so when they are little bitty, you can tell them then. As they get older, to me, they are kinda like EE, and hard when they are in a "tween" phase. I am positive if it is 10 weeks, that it is definitely a roo.