Thanks for your query.
Noted the history of farting for a long time, that you are 16 now and have trained body to hold the farts in the days but the moment you reach home start farting or if you control you can feeling internal movement of gases.
The causes of farting is excessive gases.
The cause of excessive gases are:Aerophagia
is by far the commonest cause of gases in the intestines. This is inadvertent swallowing of air and the air thus swallowed is passed to the intestines and colon
to be passed out as fart.
Another important reason is imbalance of the bacterial flora in the intestines with overgrowth of the bacteria that produce gas.
Other reasons are to have aerated drinks or consuming hte foods and beverages that promote gas production.
I would advise you the following:
Control of stress
if you have.
Stop taking aerated drinks and foods that contain the stuff like nut and so that you must have observed to increase the farting.
Send tests of blood and stool.
A course of antibiotic and Metronidazole
sometimes kills the bacteria responsible for producing the gases and hence the problems is usually sorted out.
Once the cause is found and treated or avoided as the case may be, your farting problem will be solved.