Nah, you're never to young to not like what you see in the mirror, for me I think from about Grade 6, I didn't like what I was, all the other girls where smaller than me, I was in no way a fat kid but no skin and bone either.
Like Tegan, I follow the saying
it should be a lifestyle change rather than a 'diet' since once you finish a 'diet' you inevitably go back to what you did before hand
I've stopped counting the times I've started something, lost the weight I wanted to and then gone back to my old habits.
Re: your friends, do you think that if they knew you were trying to lose kilos that they'd support you by not eating crap in front of you?
Anyways, welcome and good luck with your weightloss,