Thanks guys! I definitely need to make more medium and larger things. I have patterns for all the way up to XXL. I have made one XL and it just seemed so big compared to KS. But I have to remember that yorkies are so much smaller than bigger dogs like labs and such.
As for sizing chart, I go by the sizing on the pattern. Of course this can be altered if need be. I then do length depending on how long I think it needs to be or by how long it is requested. Basic sizing is:
XXS 8-10" girth
XS 10-12"
S 12-14"
M 14-16"
Neck is adjustable and can be altered as well.