formula fed babies do not receive certain antibodies due to lack of breastfeeding and that may eave them vulnerable to certain infections. other than that there's not much of a difference. it is a little difficult to tell without having a milestones timeline, but if he has achieved all other milestones on time and sits with support for more than 5 minutes, u can relax. starting ragi feeds at 5 months old was a little too early in my opinion. now that he is 10 mo old, u can give ragi. also try and maintain a variety in diet since babies tend to get bored quickly. u can also give mashed dal rice, fruits, juices, soups etc