My Abby is only 6 pounds too. She was 5.5 pounds when we adopted her last fall, and she's only put on half a pound since. We let her eat all she wants but she just burns it all off with all her playing, and boy, does she play! She's 14 months old so I don't expect to see her get much bigger, if at all. I used to think this size/weight was odd until I read all the previous replies but I guess not!