How much should baby gain at 4 weeks?

My baby was born at 36 + 4 weeks. She weighed 5.8lbs. In the first week she was down to 5.3. At 10 days she was up to 5.12.

She will be 1 month on Saturday. And when I weighed her at home she was 6.4. Is 1 lb a healthy weight gain for the first month? I see most gain almost 2 lbs by the first month.

My older daughter was always in the 10th and 15th percentile for height and weight until she was just over a year old.

This baby is in the 1st and 2nd percentile so far. Had 2 appointments in the first week because of her size and slight jaundice monitoring.

I know I'm just a little paranoid / overthinking. She was born a little early because of complications in the pregnancy at the end.