Breakast: Oatmeal - 350 calories, with 1 litre milk - in oatmeal and drinking - 530 calories - oatmeal and milk = 880-900 calories
Lunch: 2 chicken sandwiches - each 300k - total 600k, banana - 100k, almonds - 600 calories - sandwich, banana, nuts = 1300 calories
Dinner: Tuna salad - tuna can - 165 calories, salad - tomatoes, lettuce, cucumber, etc effectively zero - 165-200 calories
Total 2400 and you're basically still eating nothing.
Nuts and milk are very calorific - adopt both unless milk gives you acne or bloating. Carbs like bread and pasta are also highly calorific.