Does she have a cotton coat? I know it mats and tangles very easily. Sounds like you are doing everything right. I recently purchased the Chris Christensen wooden pin brush, because I liked the smaller head, and so many people recommended it. Joey hair is silky and its long only on his legs, but there are no sharp tips to hurt his skin and tangles come out in a jiffy. Here's a picture of it.
https://www.a1petsupply.com/secure_h...odpinbrush.gif. Also, make sure you always use a good conditioner, and their are some sprays that make brushing go easier. I'm sorry your having such a rough time, I wonder if she just has overly sensitive skin? She has a beautiful coat! Remember, your first step is taking the tangles out, and then finish off with a comb, so a pin brush works best for this. Boar bristles just make the coat shinny; they don't really help with tangles.