Hello ladies!

My baby is 5 weeks old and was born at 7lbs exactly his first appointment he went down to 6lbs 8oz neeext appointment he was 7lbs 4oz. My pediatrician let me know he’s teenie and needs to be gaining more weight he drinks 2.5 oz every 2/2.5 hours still wearing newborn. He’s only fed breast milk since he was born. Do I need to consider switching him to formula to have him get more chunkier? Please help I don’t want to stop but if I have to I will.

Thank you !