I'm going on holiday in a few weeks and although it's not a summer holiday so I won't be wearing shorts and a crop top I would still like to look good. At the moment in 16 and I weigh 8 and a half stone. I know I'm not too heavy but I would like to loose some weight especially belly fat and thigh fat (and maybe some upper arm fat.) What I do already-
I go gym 3 times a week (twice just gym and once gym and swimming for an hour each.)
Workout exercises once a week for two hours.
Eat about 1000 calories a day instead of the recommended 2000 calories.

What else should I do and do you think it's possible to loose that much weight with my diet plan? Thanks,