Can you please get photos of her?
She's now about 9-10 days old?
Sorry, your posts are quite long, so I may have missed this, have you given vitamins?
Sometimes Silkies especially can struggle, so she may benefit from Vitamin E (400IU) and 1/4 tablet B-Complex daily for a couple of weeks...
You can't see a tongue?
Any chance there's a hair or tiny thread wrapped around the tongue and has pulled it back? Take a flashlight and look really well.
I'm sorry she's still not thriving. Constant peeping for days on end and getting weaker, it's likely time to put her down...