Low weight gain

Billie
Had a weight check today baby girl lost weight from birth to check up went for another weight check today only gained back 2 oz doc was wanting 5 oz.  been feeding good last two days every 3 hours for about 20 to 30 mins. I have a good supply cause I am able to pump. Gave her a bottle to see how much she eats only 2 oz out of the 3 oz I pumped