It is better to avoid diapers except when travelling or functions etc. It causes rashes and retained dampness may lead to urine infections etc. Please avoid formula milk and also packaged food like cerelac. They are not as beneficial as home cooked fresh food. Give khichdi, mashed potato, sheera, upma, idli, fruits, mix green vegetables in dal rice.  Type baby food recipes 7 months india in google and you will get many options. Websiteslije Tarla dalal have some great recipes.