welcome to healthcaremagic
height depends on genetic factors and diet.
as you are 15 ,you have chances to increase height.
in your diet like soyabean,pulses ,beans and non-veg,if you take and enough of milk.
Have aswagandarishta 2tsf twice daily after meals.
Exercises like tadasana,hanging on beam,cycling,swimming will also help.
Wish you good health.