Your BMI for your current weight and height comes around 17 which is less for your height. BMI less than 18 is under-nourished.
If you want to put on weight you can eat more of Chocolates, Ice-creams, Eggs, Milk, Fish.
Produts such as cheese, ghee also help you increase your weight but they should not be over eaten as they can cause hyperlipidemia
. Hope you catch up your weight pretty soon. Regards, Dr.Ismail