If you're finding a lot more white feathers than normal, then your white silkie is most likely molting. If she is molting, that would probably be why she's not laying at the moment. As they lose their feathers, their body is trying to regenerate fresh feathers. Protein is needed for feather regrowth. Protein is needed for egg production. Feather production usually wins.
There could be other reasons, but I have a silkie currently molting (I'm finding lots of feathers, especially around the roost each morning) who is not laying.