Hopefully I can help you, I'm a personal trainer and LOVE training myself.
If you're looking to loose weight you are best to do it in small steps, if you loose the weight all at once it's much easier for your body to retain calories when you next intake them, from high caloric food sources.
I'd suggest doing high intensity interval training if your looking to loose weight, these exercises are the best for this. I can point you towards www.zuzkalight.com
and you could try some of hers.
Don't bother with carrying heavy books to school, unfortunately it's not enough to burn enough calories, 1lb of bodyfat contains 4000 calories so imagine how hard you need to work to loose weight!
Diet wise, so long as you are eating clean, little but often you should be fine, don't concern yourself to much with protein as this is a 'muscle-building' source and it's not actually doing anything for you if you are not training to gain muscle. It can also have the reverse affect.
Also drink plenty of water, it actually helps to break down fat molecules which is a bonus!
If you want to know anything please ask.