my daughter talks laughs, tries to grab stuff, sits up with support, stands with support, holds head up great, isn't rolling over quite yet but tries to lol and I only breastfeed so no solids yet

My son is 5 months and doesn't roll over yet and doesn't eat solids. I will start spoon feeding him oatmeal more to get him used to eating by the spoon but my mom who is a pediatrician said to start solids at 6 month. A 3 month olds digestive system is not ready for solids yet