My daughter gained 3 lbs in 3 weeks and pedi wasn't remotely worried. He actually said, sounds like she's a great eater. I EBF as well.
She was born 8lbs 2oz and then was 8lb 10 oz at 1 week appt Just had her 1 month appt yesterday morning and she was 11lbs 10 oz!!! :) and she also grew over 3 inches. We think they didn't measure her accurately at the hospital though.. supposedly she was born 20.5 inches and was 23.75 yesterday.