We have 3 silkies, about 7 weeks old. We've been trying to guess what sex they are since we first got them- I want to see if any experts here have any thoughts as well. The white/brown and the dark ones have very puffy heads. The while one doesn't have a puffy head. That's the biggest difference between them. Dark one is the biggest, then the while one, then the white/brown one. What do you guys think?