Baby slightly kurus for her age

Hello, my baby baru masuk 5months 3days. Kelmarin ad buat checkup to take her 5months vaccine. Her length was 66cm which normal i tgk dekat her age but her weight was 6.2kg. Isnit normal? My question is, How can i increase her weight? Im giving her fully formulated milk now as im working mother. She’s my first child and im a bit clueless on this. Can help me? Tq so much. #pleasehelp #1stimemom #firstbaby