My DS is 8.5mths and just over 19lb I think his medium motherease wraps are just starting to get on the small size for him (they'll go on for a bit longer but length wise they are starting to get on the short size)he's a light/longlish baby (25th centile weight/75th length). Which size up would be best for him the med/large or large - I'd like to get the large as they will obviously last longer but as he's quite slim I don't want to get them if they are going to be loose and we get leaks. Thanks for any advice.