Chocolate Lab puppy size

Question
My female labrador is almost 6 months old. I know labs vary in size, but she seems quite small. She weighs 45 pounds and is 18 inches at the shoulders.  I thought that while dogs will add bulk after 6 months they were about full grown by this time.  If this is true she is way below the standard height.  

Answer
She shouldn't be done growing, but will slowly gain some size.  I won't say she will reach the 21'' minimum for the bred standard.  I hadn't realized how much my puppies did grow after about 5 months until I had an older dog in the house to compare them to.  Several of mine haven't been big enough at 6 months to share a 50 -100 pound pack of Revolution with the older dog.  

Don't make the mistake of over feeding her to increase size.  That will just give you a small, fat dog with poorer joints.  Best thing for a dog with a long active life is to change over to adult chow and keep them lean.  No chart can tell you hat a dog should weight, only its ribs.  See http://www.puppychow.com/products/popup_body_condition.aspx