I think Charlie is fine. My Louise is a 13 in, and weights only 17 lbs. I call her my little "imp" She is so tiny, but fast as a speeding bullet! Thelma, on the other hand, is a 13 in and weighs 22-23 lbs. She is a little "tubby" when she's sitting, but when she has "good posture" she looks great! Vet tells us they are both fine. So, don't worry. Less weight will keep her spine and heart healthy. Beth, Bill, Thelma and Louise