I really need help, i'm putting on weight, rapidly.?

Hi. I'm 15. I've putting on weight recently, and it's really getting me down. I know, I only have myself to blame because I usually make the wrong choices. But I need to loose weight, im nearly 13 stone. I do well until someone offers me a sweet for example, I hope there is someone with a similar situation, cause' I can find a bit of incentive to encourage me. I do taekwondo twice a week so I am quite built.. not saying that's an excuse for my weigh problem, but it's getting to a level of severity when my Mum says I might need proffessional help, I don't want to go down that road cause' I want to be able to solve my own problems because it's my fault i've put the weight on..