seriously need advice

So my son was born at 6 pounds 10 ounces. Leaving the hospital he was 6 pounds 3 ounces and at his first visit he was 6 pounds 5 ounces with just breast feeding. All has been good and nothing has changed with how I feed him. He fills up diapers fine and never acts uncomfortable. So today at 2 weeks he weighs 6 pounds 2 ounces .. what the hell! He's been eating fine.. every 2-3 hours from 15-20 mins. My supply is great too. I pump while feeding him three times a day and get 2 ounces every time. I just don't understand what is going on. Even the doctor doesn't understand why. He's deff eating because the doctor had me feed him for 15 mins and re weigh him and in 15 mins he got 2 ounces