2 month check up

My daughter had her 2 month check up and doctor wasn’t to happy with her weight gain . She was 8lbs 8oz at birth and now weighs 11lbz 15oz & 23in long. She’s eating 4oz about every 3 hours And gives me about a 5 hour stretch at night and after that it’s back to every 3 hours. She wants us to bump up her feeding to 5oz…which I’ve tried and she literally drinks her 4oz and spits the bottle out. Any thoughts? I think she’s perfectly fine and chunky but I guess not.