my puppy is exactly the same size as yours & i had the same problem. i did find & buy an xxsml & it still didnt fit properly! then someone suggested cindy, chattiesmom on this site. She makes harnesses made to measure for your pup. I ordered one & it is a perfect fit and really cute. If you put harneses in the search engine you will come across a thread that mentions her harness & pictures of them & a link to cindys site to order one. lots of members on here use them. Honestly for a little dog they are your best choice |