Is my baby too skinny?

Lauren • Had my sweet girl 02/22/20 - 5 weeks early due to rare genetic disorder💗 Had my handsome man 09/30/22 - 3 weeks early due to low birth weight💙

She is almost 3 months. She was last weighed at her 2 month appt and they said since she’s so long they’d like to see her gain more weight for her length. Sometimes I feel like I don’t feed her enough or she’s too skinny. I feed her 5.5oz every feed but I still feel like she’s so lean. I see other babies her age who have rolls and are chunky and she’s so skinny. Is 5.5oz of formula enough at her age?