German Shepherd size and coat

Question
Hello, I am inquiring about my 3.5 month old German Shepherd. He
weighs about 30 pounds, and behaves and looks like a GSD but his
tail is still noot "fluffy" and his black coat is very short and shiny!
He also has tan markings.(A spot on his tounge, like a Chows, but
definitely has no qualities that resemble that breed)  Is his weight
average for his age? Could his coat and tail possibly fill out still?
His ears are up and crossing at the top. I'm just wondering if I may
have a mix? I have a female GSD and her coat just seemed a lot
fluffier at his age. Any infomation for me? Thanks, I am just
curious.

Answer
It sounds like he is going to be small for a Shepherd.  As for the coat, there are variations within the breed.  Some Shepherds have shorter hair.  You might be able to find more on this at www.akc.org  Trouble is, they are too oriented toward dogs comforting to their breed standards.  They also provide some links which may be more useful.  

Many ''purebreds'' do not look like their breed standard.  This is partly because there are genetic variations within all breeds.  Another problems that a female will mate with any male she get a chance to even after being bred.  Some people fail to keep the female secure after being bred once, and at least part of the litter may have another father.  The only real way to sort things out is a DNA test.