It's probably not as bad as you imagine kezia. When I used to critizise my self, my elder sister used to say that I stood too close to the mirror & do you know what, she's right!
Difficult to get rid of if they are there because of your face shape, ie. nothing to do with being fat. I know you can get rid of a double chin by going under the knife, but operations always carry a risk. Clever make-up can disguise them.
Kezia, posture can help a lot. Try to hold your neck nice and straight. If I catch sight of myself in a mirror when I am feeling jaded and have allowed myself to slump my chin looks awful!
i think i've answered this before. It may sound a bit old-wives-tale-ish but double chins and jowels are known to be attributable to alcohol consumption and it is wise to give up the grog if you want to lose the jowels. This may sound daft but there you go - i have been off alcohol for a fortnight now (dieting) and my dad said the other night that my face looks thinner these days.
At 15, we are very self conscious and tend to try to hide what we are self conscious about. This just draws attention to it. So hold your head up with pride. If your scar is very bad you can get help to disguise it on the NHS. Make up your eyes and lips to look so beautiful that noone will even notice your chin!