Help with sexing

I have 2 silkie chicks about 11-12 weeks old but could be younger... I have had too many maybe girls or maybe boys... need to know for sure please help
One has blue ear lobes one has purple/mulberry ear lobes and one is distinctly bigger than the other...

Silkie chicks Physical Characteristics.
After about 6 weeks the cocks comb is medium size and pinkish, the pullets is small and yellowish.
 The cocks legs are sturdy and long, the pullets are smaller and shorter.
 The cocks has a thin line of stub feathers down the center of his back, the pullet has more advanced feathering along the center of her back.
 The feathering in the cocks side of neck, flank and crop areas are poorly advanced, the pullets feathering in these areas is well advanced.
  In the cockerel the wing bows are bare, in pullets the wing bows are covered with small feathers.
This is more helpful if you have both sexes to compare.. Other than that, wait till one of them crows or lays an egg.