2-3 pounds normal weight for 6 week old?

I ordered a dobie from a pet store, and they said to put a 300 deposit and they´d have one for me the next day. it was 3 days later, they called and I went over there, and it was a boy (I´d asked for a girl) and was in a small cat crate. Cute sweet puppy, but tried to nurse my shirt immediately when I picked it up and was starved acting. Ribby and pot belly, and maybe 3 pounds. Black and tan, tail cropped. It´s little head maybe the size of a golf ball with a nose sticking out. I said, "is this going to be a full sized doberman??" They insisted yes and told me to pay another 350 which I did, and took the little guy home. I looked at pictures on the site and this dog doesn´t seem big enough. Took it back and the lady who owns the store was irrate and said the dog would grow, it´s only 6 weeks but if I want a bigger dog she will take it back and get me an older one. I said, I don´t want "older" necessarily, I want bigger for the age of the dog, this one doesn´t appear to even get close to breed standard. She said if I wanted a pedigreed doberman with papers that met breed standard I would pay twice more. This one she says doesn´t have papers. Is this normal???