If birth weight is normal and growing well, normal weight is around 13-14 kg at 3 years. So your child is little underweight, nothing to worry. Feed frequently that is small meals every 2-3 hours and not three times meal. These small meals can be anything like a banana, an egg or fruits or your meal itself. Add ghee to your diet. Eggs are also good.
Next Steps
If he is active and well, has no recurrent fever, chest or ear infections, then there is nothing to worry. Usually toddlers, this age run around and play more. Height will increase, weight will usually remain stagnant
Health Tips
If your child had more weight before and now is losing weight then we have to do blood tests accordingly