Talk to Pediatrician on Overeating In Children

My niece who is 7 months old only eats a lot .. I have checked her blood sugar levels many times but that is is normal range. Her weight is 7 kg and she’s an active child but sometimes she overeat to an extent that results in vomiting. I have never seen her satisfied and full in these 7 months . I am very tensed about her so is my sister. What are the possible causes ? Should I go for deworming?