What I've found that helped me a lot when I had the urge to starve was to just force myself to eat something really healthy nutritious. Just take a couple bites and see how you feel. You'd be surprised at how much easier it can be to control that particular urge when you focus on healthy good-for-you foods. It doesn't make it quite so bad, and it is very important to keep eating despite wanting to skip meals. It will give you the energy you need for sports, instead of feeling drained and zombie-like. (I don't know if that has been a problem for you in the past, please forgive me if I assumed too much )

As for your parents... that can be the toughest challenge. Often they don't see it, and if they do they are in denial. It's a damn shame that for some reason nobody will believe someone with an ED until they look like they are on death's door, and by then it is very VERY hard to recover. You need to keep pushing them and telling them how you feel. If they still don't want to talk about, ask to see a therapist so you CAN talk to someone who will listen to you and believe you. These are very real thoughts and emotions you have, and they are not to be dismissed because someone else doesn't believe they are important. Show them http://www.something-fishy.org/. It has helped me understand a lot about my disorder, and tremendously helped my partner in understanding what I was going through.

As for the throwing up? Please don't do it. That is a one way street, and once you start it is VERY hard to stop. Every time you feel the urge think of how icky it was the last time you tried it. Also, think about that fact that you are wasting your time seeing as 70% of calories are absorbed upon entering your stomach, so you're not doing much good anyway. If you focus more on putting GOOD things into yourself, you may not see your meals as being purge-worthy. Please know that it is very dangerous for your teeth, gums, throat, stomach, and especially your heart. It is simply not worth it, and I hope that you can find the strength to resist.

You are strong, and you can fight this. We all can.