Should i jelq, what does it do?

I’m 16 and my penis has been around 7 1/2in, 2 inch wide since like 7th grade… is this a problem will it grow some time or something and should i jelq? what can jelqing do will it decrease my girth? and if i ever stop doing it will it go back to my normal size? and is there anyway i can shrink it
i ment will jeqluing shrink it… not that i want to