My male looked small (to me, in reality he wasnt) up until about 6 months. At 6 month he started gaining height pretty fast. In 3/4 months he put on about an inch or so a month. He is 9 months now, about 25 inches (at the shoulder). They all grow differently and at different rates. Give you pup time, they don't stop growing and filling out for almost 2 years!