I see you have completely disregarded sire Relic's advice. I am sure Mr. Maki will be along to school you in the err of your ways but allow me to point them out and also perhaps give you a plan to follow.
Regarding fat chicks. Fat chicks get less attention, thus they will do more things to gain said attention. Hence you can use les fat chicks as "starter girls" persay. "Quantity over quality" as is the saying (Maki).
Now for the plan.
Find a fat chick** she is friends with, don't say she doesn't have any fat friends because we all know that isn't true. Every group of girls has one larger friend in their midst.
Next court said rotund young lady. Be absolutely sure that your "best friend" knows about this, however make sure you don't make it over the top (a good example of how not to do this is how you bumped your threads every few hours, casually mention it once or twice if need be just make sure she knows who you're seeing). As you see more of the fat friend give your friend less attention, let her know she isn't the number one priority anymore, especially don't react when she makes out in front of you.
Soon she will begin to wonder why you are giving so much attention to a female of lesser attractiveness than her and will begin trying anything to get your glorious attention. At this point you'll want to lap up the attention she will no doubt be pouring on you but still give her very little. If you cave now she'll be happy she's gotten your attention again and you'll get nowhere.
Make sure that the fat friend has a great time, all this positive feedback will get around and back to your "best friend." All of this combined will make her yearn for your attention again and when she inevitably breaks up with the boyfriend (probably after a month or two at most) it is now time to give her small doses of attention. Keep yo-yoing her for a bit and eventually she'll throw herself at you. Hit it and forget it, or hit it and look for better.
Now you might be wondering why I said move on. I know you will not believe me when I say it but there's a 99% chance you're not in love with her, from what you've said it sounds like infatuation. We've all had one at your age and they're stupid to continue. All that happens is you waste time and turn down quantity for your idealised "quality."
*Of course it goes without saying the entire time you are with the friend you should be honing your skills. This is the time to get all of the beginner's awkwardness out of the way, master your equipment and moves as well as her equipment.
**Note fat can be replaced with ugly, the point is to find some female less deserving of attention (at least in your "best friend's" mind), it could also be an enemy.
Most of the ideas in this plan have been presented in this thread by many fine men. Take our advice and utilise it to your advantage. Instead of making a thread like this go out there and rack up some quantity. Its really not that hard to get girls in high school, follow the golden attention rule and you'll be swimming in them.