Baby drinks little after solid

My 5.5 month old is on solid. As she is in IFC she would have breakfast, lunch and tea time Throughout the day she only drink 300ML or less than that. Ive heard that until age of one baby’s main nutrition is milk but she has been refusing milk 2 weeks after start solid. Idk what to do 🤷🏻‍♀️ i believe 300ml is not enough for baby (throughout 24 hours is 300-400ml sometimes) Any mummies experience the same?