Partridge Cochin Not Feathering

[BHFarm]

This partridge cochin is 8 weeks old and looks nothing like her siblings. I know some birds can be slow growing but this one is almost naked, her bum looks worse than her front. She isnt getting picked on. Is this ok or is there something I can do to help her? She doesnt seem to be in pain but I dont want her to be naked forever, =)
Also, do you think this is a roo or pullet?

 

[BHFarm]

Pics attached