We had an appointment for Alex today. He was 10lbs 10oz at birth, and 10lb 11oz at 3 days. Today he was about 3.5 weeks old, and already 12lbs 11oz. So 2 pounds in 3 weeks. He also gained quite a bit in length in those 3 weeks - from 21.5 to 22.75!
Hope your appointment went well - mine was almost nightmarishly crazy, with my two older kids tagging along and acting like wild monkeys inside the exam room! But at least our doctor is nice.