Breast feeding

My baby will be 2 months July 1st and she doesn’t seem like she’s gaining more weight.. like i see other babies are.. she eats every 2-3 hours 3oz of breast milk while I’m at work and she’s only breast fed.. last time we were at the dr she was 9.5lbs she has to be about 10.5 now it more.. but she still doesn’t look chunky or filled out.. she’s still in nb diapers they are right in her but 1m is too big.. she’s in 0-3 clothing now and some nb is bigger than the others we have. Any suggestion on how to have her gain more weight? What should I be eating? FTM