Help me sex my silkies

[Flockie]

I have 3 white silkies 13 weeks old . The largest ( David Bowie ) crows . The smallest ( Llana ) - pictured alone in the 2nd pic crowed today . The middle silkie ( Emilio ) - who is the bossiest of the 3 has not crowed . Please help

 

[sourland]

Silkies are tricky for sure, but all appear to be cockerels.