11 kg in 22 months can be normal. It should be 4 time of his birth weight by this time. Although you are worried about the weight,  you can add ghee or butter in every meal

Hello, Your child is in the borderline for underweight Continue breast feeling You can alter his diet at home Nutrient-Dense Diet Add healthy fats: Ghee, butter, avocado, nut butters Include protein: Eggs, dairy, pulses, cheese, chicken, fish Frequent meals: 3 main meals + 2–3 snacks per day Avoid empty calories: Skip sugary snacks, juices, junk food

11 kg is just below the normal limit - what's his height? Just give him proper nutritional food. You can give him pediasure/nan-grow with milk

Continue offering regular, nutritious meals and snacks. Focus on calorie-dense foods appropriate for his age, such as healthy fats (avocado, nut butters if no allergies), full-fat dairy, and protein sources. Do not force-feed.