4 hour schedule

So, one thing I don't like about nursing is that you never know how much the baby is getting. I decided to do the 4 hr. schedule for about a week and see how his weight was doing. He was almost 8 lbs. 1 oz. at the doctor 2 Wednesdays ago, so he should have been at least 5 more ounces than that 10 days later on Saturday. They gain about 1/2 - 1 oz. per day. So, I weighed him Saturday and he was almost....10 pounds! What in the world????