Sounds normal to me, my male was only 56 pounds at 6 months. Whatever weight she is HEALTHY at is good. Dont go by numbers. If she is not skin and bones, but you can feel her ribs, she has a 'tuck' etc, it is a good weight. if she is chunky/flabby etc, she is too much. Hope that helps.
Penny is 7 months old and weighs 48lbs... at 5 and 6 months old she was 43lbs... I will have to agree if you can feel the ribs and has a nice dip after her ribs then she is fine but if she is over chunky she might be too heavy. Penny is perfect, she was chunky when she was younger but is lanking out now lol
They are all different ? my girl is 54 pds just turned one- very lean, fast
My boy is 7 months an 77 pds solid muscle very powerful. My vet says they are each perfect no fat on either one...two very active pups! Lol