Losing weight problem?

i'm 5ft 1 and 108 pounds, and im 14. i not fat, but i have big thighs and flabby upper arms. i need roughly 1400 calories a day to maintain my weight when i don't exercise. So heres the problem. I want to get thinner, but i don't know how much to lose. I have a plan to eat 1000-1400 cals a day and exercise every day and i have 6 weeks till schools back on. So what would you's say i do? not worry about weight, but exercise and tone up to the size i'd be happy with or lose a certain amount of weight, like 8 pounds and then begin toning and maintaining afterwards?