Get confident and start by making yourself get into constantly awkward situations. Cashier, drive-thru, customer service jobs come to mind at first because you're so young still. They'll get you accustomed to the INTENSE embarrassment that comes along with being an absolute buffoon. You'll get used to it. And that's when you can begin to work on your stutter properly without your own judgement when it happens because you yourself are your biggest critic. Once you get that fool out of the way, pff, it's way easier. Just get over yourself and you'll overcome. Sucks, but it's fun in it's own way.