Trying to lose 20 or more pounds this summer help please?

hey you guys. i am trying to lose 20 pounds or more this summer. I am not sure this is a good idea but when i am done with it i guess we will all see. and it is so much more easier gaining weight than losing. i am an LA teenager and yes i am influenced by all those models. i workout a lot and i am almost 14. i basically just well not halfway done with puberty and height but anyways. my measurements are 35-26-37 everyone compliments me on my figure and say i am skinny. but i am not just statisfied because i weigh 140 pounds. yes i am kind of muscular and i play sports but i do not think that's any excuse. so i am planning this summer to be like 120 pounds or less if possible. because if i get skinnier i would look more like an hourgl. any ideas. i think summer is the greatest time to lose weight because when i return to school everyone is like wow. please do not recommend supplements because i can not take them. i am not obese do not get it wrong. i am just a rich teenage black girl with a dillemma. i've got the determination i jsut need enlightenment