My 11mth old never has liked formula. Tried whole milk doesn't like. She weighs only 15lbs. Eats baby food. How can I get her to gain weight. Normal?

Needs assessment. Sounds small for age. May be failure to thrive which has many etioiogies and would need to see pediatrician to assess. Social issues, gastrointestinal abnormalities, chronic illness, metabolic disorder, intolerance to milk protein, infections etc. Infant is avoiding liquids.Could be related to gastroesophageal reflux. Liquids more likely result in reflux and irritability of esophagus and refusal.