Hello dear, First of all remove all myths & misconceptions from your mind about masturbation. In fact, Masturbation is completely normal & doesn t have any bad effect to the body and mind, unless you are addicted to it. Height of an individual is determined by Genetics, Environmental & Nutritional factors and Hormonal factors (most important the Growth Hormone secreted by pituitary gland in brain) An individual stops growing in height after the fusion of the Epiphyses (growth plates) of the long bones, which occurs by the age of 17-21 yrs in males. So...as you are 15 years old now, there is still a good chance of further increase in height. An X ray for bone age determination can be taken to look for the fusion of epiphyses. Make sure that you are taking a healthy & balanced diet, exercise regularly & avoid stress. Protein rich diet like soya, groundnut, pulses, etc should be incorporated in your diet plan. Wishing you Good Health. Take care.