This is what you should do:
1. Don´t lissten to the nubs sitting around mmo telling u to get friends and stop being such a no lifer.
2. Does you school matter at al yet? in sweden atleast u can just sit around for about 10 years until what u do actually have a serious impact on the rest of your life
3. Parental control... It is actually quite a good way because it will dissconnect u from the game after a special amount of played time.
4. Start playing an instrument or sport or w/e it´s fun its good for your body (sports) and good for your brain (music) and u meet new ppl.
5. self disciplin is important u have to tell yourself that u have played enough! dunno how to train this though...
6. follow all above and you might find yourself in a better situation : D
Just remember quitting is not an option if you enjoy the game just take everything in moderation, even world of warcraft!