How do I loose my love handles and flatten my stomach?

I'm 15 years old and come from england, and I dislike my body. I am not obese but I'm not skinny. The main parts I want to get rid of is my love handles, stomach fat, and the top of my thighs. I don't know how much I weigh but I think its about a 11 something stone, and I would really like to get down to 8 stone at the least. I am normally a size 12 in clothes and a 10 at a struggle I would like to get into a size 8 or fit perfectly into a size 10 without a struggle, I really want to loose all this weight by next year in july for my prom, but I would like it to go more quicker than that as I felt disgusted with my body. I no things like you have to do exercise and eat healthy, but when I do this I never see any improvements. I normally, eat 2 crumpets for breakfast, a salad sandwich for lunch and what ever my parents cook me for dinner, and I just don't understand why I weigh what I do, I'm not someone who trashes out on junk food and I do exercise when I can. so I would like your advice on how to slim down my love handles, stomach and thighs, I would also like to know how to tone my bum, thanks