6 month check up

So my baby had his 6 month checkup on Monday. Born 6/3/16. He was 18.5 lbs, 25 in 3/4 height and 18 inch head. The doctor always says at everyone of his visits that his weight is great (on track)  and his head is bigger (guess normal for him)  and never mentions his height or says it's ok. I am concerned about my lil guys height. Since 4 month visit he only grew like a 1/2 inch. She told me not to worry as they think his 4 month visit they measured him a little longer than he probably was. He seems short compared to other babies...some are almost 2 inches taller. What about your 6 month old measurements?