Baby

Hi Mummies! my lo is 4 months old and is only 4.8kg now. During her 3 month check up DR said she was in the 3% percentile. She isnt gaining weight and its very worrying for me. I DL through the night and also bottle feed day time. she drinks about 90-120mls every 3 hours. Besides that good diaper output and she is hitting milestones. Should I be worrying about the weight or isit okay? Please advice. Thanks in advance!