I think I'm done with girls for the moment(it seems none of them like me)?

Your last paragraph says it all. Look, your 15 and it isn't a big deal. Plus its better when friendships (relationships) just happen naturally than when you try too hard to make them happen. Focus more on what you can do to better yourself for you not anyone else. Don't forget at 15 your still pretty new to all this, awkwardness is inevitable, its not like your in your 20s. Your right, they aren't all that serious anyway and only take your focus away from your studies, sports or whatever else you like. Sounds like you have a good head on your shoulders and eventually, in time, some nice girl will see that.