If your academic success has been driven by your wanting to get good grades and a high class rank rather than by a desire to become a more learned, educated person then I am pleased that your discontent has arisen. Maybe you've been devoting all this to time getting great grades because that's what your family expected of you. Maybe you've allowed yourself to "settle" for being an unwilling leader of a group of girls because it's easier than dealing with the possible disappointment of not fitting in with these more "exciting" kids you spoke of.
I don't think that you need to stop doing well in school or ditch these girlfriends to feel better about your life. But I do think that you need to question why you feel so burdened and disappointed by the school and social life you are leading. You need to identify what activities, academic and social pursuits would bring you a good feeling about yourself. Trying hard at anything will not bring you down as long as it's something that matters to you. Blaming these girls for not being exciting or leaders is off the point and unfair. They are who they are and you either accept that or stop thinking in a condescending way toward them.
If a person your age really examines what's going on under her obvious frustration and disappointment, she has a great chance to become who she really wants to be -- not who she feels compelled to be by others. It might help you to sort some of these feelings out with an adult who you value and trust or a therapist. I'm not saying you need therapy but that sometimes a couple of conversations with a good counselor can bring things into better focus and provide you with the support and optimism to make good life changes.
Thanks for writing. I'm betting that your life will be better in all aspects if you keep asking the right questions of yourself and get some support.