From the measurements you stated you only need to gain 30lbs for your height. It is important that you gain the weight slowly because you are underweight. A 'cheap' way for extra calories and protein is have Carnation Instant Breakfast as a milkshake or make a milkshake out of ice cream, milk, and fruit. Drink 1-2 a day and you will gain weight if you do not have any medical issues that caused you to lose weight. Thank you for your question.