Are there other reasons, besides size that you think she might have LS? What were her Bile Acids? I have a healthy little one, and a 4.5 lb boy who has liver problems, he had a really hard time putting on weight, and refused to eat.
Size can be determined by many things, not just the parents but the grandparents and g. grandparents etc... My little one is healthy but half the size of her smaller parent... I don't really worry about the actual amount that mine weigh but if they are thin or chubby for their own frame
As far as I can tell your girl looks healthy, but it is hard to know without seeing her in person.