Get a good conditioner! It almost impossible to keep a yorkie's hair tangle-free without one. I use Wampum products which are developed by a maltese breeder in SA and they're amazing. It sounds like any conditioner will do at this point for your puppy. Do some research in the grooming section to find a good product that other yorkie owners in your area recommend.
Also, what type of brush do you have? It is definitely worth investing in a Chris Christensen or a Madan brush. I have a Madan one and I love it! It makes grooming so much easier and it doesn't hurt their skin when you brush them out. Most other brushes will damage their hair and skin.
When you comb her out daily, do you have a spray you use to moisten her hair? You shouldn't be combing it while it is dry. You can make a spray yourself by combining some conditioner with water in a spray bottle or you can buy a ready-made spray.
I hope that helps
