3 month old Australian shepherd weighs 27 pounds?

Question
we just got a 3 month old Aussie, and she is already 27 pounds! is this normal?! or is she just going to be a big girl? she is most definitely not fat, she is as healthy as you can get a dog. trust me, i know a fat dog when i see one and she is not fat at all. so my question is, how big will she be when she is full grown!?

i want to train her how to pull a sulky/cart. will she be large enough to pull one with a 130 pound person it is when she is 2 years old?

Answer
If you wanted a carting dog, I would have suggested a Bernese Mountain Dog or a Newfoundland, not an Aussie.  Personally speaking, I would not ask a dog of medium size to pull a person in a cart.
As for her size, I cannot predict it, not knowing her pedigree, but your veterinarian might be able to do so by looking at her current stage of growth.  If you purchased her from a responsible breeder, the breeder should have a very good idea at what size range their dogs normally mature.  Your pup does sound large for a female of that age, and, just guessing, if she is a purebred, I would say that unless she slows down growing that she might reach the 40-50 pound range.