Hello
I appreciate your concern
Excessive
Masturbation at very young age can leads to affect psychological development and overall well being over the period of time
Less height can't be caused by this only
Height of an individual depends on various constitutional factor like nutritional status and genetics
I would advise you to control on your urge to masturbate
If you can't control it than
consult a psychologist for behavioural therapy and counselling
Concentrate on your study
Exercise regularly
You can very easily reduce your belly fat by regular physical exercise and dietary restrictions
This is not the age to be
obese or overweight
Have a circle of good friends and enjoy your life
Please feel free to ask for more clarification,I will gladly answer you
Best wishes