This may of been asked and I missed it but did she not offer you a return guarentee if things didnt work out? From what I have read on here the responsible people do that because they want to make sure there puppies are happy in their forever homes. Does she not have another puppy to replace this one with? They really do look like different dogs to me . And according to the growth charts that is a lot of weight to gain in one month.
it really doesnt sound like anyone in your family is bonding with her and she needs to be taken back by the breeder and placed in a home with no other dogs.