good evening, a boy child of 11 months average weight should be around 10 kilos, so do not worry about that. secondly , do not feed the child with junk foods in between the main meals time, the cows milk and duration should be reduced and more of solid food has to be included , avoid bottle feeds if u r practicing, do not dilute the milk with water before giving it to the child, make the meal time more interesting by telling him some rhymes and diverting his attention so that he eats food with interest, mainly spending time with the child and dedicating ur selves as parent is very important. get his hemoglobin
levels checked to rule out anemia
which is the main cause of his lethargy
and disinterest towards the food. a thorough checkup by a doctor to check the childs anthropometry is important before any further steps are taken.