My yorkie is a big yorkie. He's about 8 lbs, not done growing yet and I'd say just has tall and long as yours. Yours must be really skinny that seems aweful tall and long for no more than she ways. I found this websight that has some nice purse carriers for a good price. Logan fit in the med. (16" x 10.5" x 7"), but just barely so I'm gonna order him the larger size now so he has more headroom (he fit pretty good except it was a little short for him).
http://www.doubledbrands.com/mepetca.html