welcome to healthcare magic, height is primarily determined by genetic and hormonal factors with profound influence environmental,nutritional and last but not the least psychosocial factors. height 5.4 is not bad at all. but important thing is to keep healthy,energetic and achieving a ideal BMI. your BMI is 15.4 ,much less than standard as per your height and weight. for you kind information, BMI Categories: Underweight = Normal weight = 18.5–24.9 Overweight = 25–29.9 Obesity = BMI of 30 or greater so try to gain optimal weight,have balanced food specially rich in protein, a lot of fresh fruits and vegetables, get aerobic excercise. steady increase in weight is preferable to robust growth. hope the answer of the question.