Thank you for your query,
I advise you to exclusively breastfeed your baby till the age of 6 months.
is the best method of feeding and it is having many advantages like easy digestibility,
anti infective properties, nutrient properties including for brain growth.
Putting hands in to mouth is not a sign of hunger in infants and usually they put hands into mouth for exploration and it is one developmental stage.
If his activity is good, passing urine 6 to 8 times per day and weight gain is normal, breastfeeding is sufficient and continue till 6 months from there onwards you can start complimentary feeding in addition to breastfeeding.
Hope I have answered your query.