My son is 8 months old. He'll be 9 months on the 18th. Right now he is 21 pounds and he is in size 5 diapers!!! I've tried different brands and he wears the same size in all of them. He has chubby legs and his stomach isn't all that chunky. Is there a different brand I don't know about that will fit him and his legs? I'd hate to go to size 6 because they don't have much in a box or a pack. I've tried the pull up diapers and he just looks like a "stripper" with half of his butt crack hanging out but they are MUCH more loose on his legs. Any suggestions?