Hi I Have A 8 Week Old. She Was 16

Hi I have a 8 week old. She was 16 days early. weighed albs 7 oz. Went down to 4 lbs 8 oz and had a slow time achieving her birth weight maybe 3.5 weeks at 1 month she was 5 lbs 15 oz, today 30 days later she is 7 lbs 2 oz. She looks and acts satisfied, her head and length are growing but she is still below 5% on all charts. I am a 48 year old 4th time mom who is breast feeding. The dr wants to supplement more, she takes between 2-4 oz before bed time ( she sleeps 6 hrs at night). Could that be her normal?