I am 143 pounds and i am 14 and i want a flat tummy and i am 5’2 and i want a flat tummy FAST so I need some help. No medication and i want to know a really good diet so please HELP!!!!!!!!!

i want to be skinny, but not too skinny, looking good im 12 and 145 lbs, i hate being made fun of, and i have a slow metabolism, but not enough to go on medication, ive tried like 1,000 different diets and none of them work, i hate my life, i need to save myself by getting thin, help please!