chattiesmom makes a silk harness, and everyone has had nothing but wonderful things to say about them. It sounds like the silk harness would be very good for your baby as the one she has now seems to be causing discomfort. My yorkie also has a longer body, and we also want to prevent matting while in their harnesses, so silk is the way to go for us
I'm actually going to be ordering the silk harnesses for my furbabies from chattiesmom very soon. Good luck!