I'm pretty sure it would be ok - the sweater is 15 inches from the hole at the neck (where you can attach a leash to the collar through the sweater) to the end. According to your measurements t would about 3 inches short of the end of her back. My dogs are males so I like everything short so as not to interfere with the number 1. But you obviously don't have that problem ;-)
I am going to be in LA at LAX for a while, because I'll be on my to Alaska and I have a layover there! :) I want this so bad, my little Dachshund would look so cute in it! I will have enough credits to bid soon! :)