I agree with Diego, you sound perfectly healthy to me
To be a size 7 or larger doesn't make you overweight, it's called being HEALTHY! haha..
But if you still want to lose weight (although you definately don't have to), the biggest difference is not going to be some miracle pill or crash diet to drop those pounds.. it's all about a change of lifestyle. Or else, all the weight you lose from the diet is gonna sky rocket right back up once you're back to your normal regime.
The best thing to do is try to replace as many meals and snacks with fruit and vegetables as possible (try to get in a variety, and remember that although fruit usually tastes better, it has more sugar too!). And remember to drink plenty of fresh water! You might feel bloated or "fat" for the first week or two, but your body should quickly adjust to the extra fibre. Although only eating veggies, whole grain and low fat may seem a bit icky at first, it REALLY pays off - and if you're like me, you're gonna find it hard to go back to the normal foods you used to consume (like sugary cereals, occasional candy, etc)!
Another thing is exercise.. sorry to say, but it's a bit unlikely you'll ever reach your dream weight by only restricting what you eat, unless you become anorexic.. (which is never a good thing D: ) Great to hear you play volleyball! Some exercises that will really shape up your entire body are swimming & running - it doesn't take much, just 20-30 minutes a day is enough
Best of luck and Stay Healthy!!!