I'm losing weight and need to find a dress which is slimming and one which I can fit into?

i'm 16 and recently joined rosemary connely's fitness cles and over 4 weeks I have lost half a stone, i am now 10 stone 10 pounds and 5ft3. I've mainly lost weight in my face and upper body. There is a 'winter ball' at school soon and people wear short dresses, this means I'll have to show my legs which are huge. What type of dress would be the most slimming? How much more weight could I lose until late november? I'm losing roughly a pound or two a week and thats with little exercise. What exercises are best for me to lose weight of my legs, arms and stomach. How can I look hot? What dresses are slimming?