If a 15 year old girl is skinny and 5'2 would she have a smaller bladder than a larger person? do smaller people have smaller bladders?

Yes and no: Bladder size is relative to basic size when you look at lean body mass, but it also varies with use.Those with a tendency to retain or hold urine will have a more generous volume and those who tend to eliminate frequently will have less.Those with problems leading to stool accumulation, retention & constipation & those with obesity can squeeze down the functional capacity.