Don't worry, dear. I've felt this before. I'm the kind of girl in my group of friends who can get teased and then react profusely, but they know I'm not serious when I get mad. (if that sentence made sense.) But it hurts sometimes, you know? When they go too far and they don't realize it.
Thing is, everyone is insecure. About something. You're young, and people are going to change and there's nothing you can do about it, so I guess you gotta just go with the flow. Just do what you think is good for you. :)
Regarding the popular thing, well, this is exactly what people want you to be thinking. You're thinking about them. You're wondering what makes them tick and why people admire the "popular" kids. To me, that's just as bad as worshiping them. Best thing to do is just...not care. Indifference is the opposite of love, after all :)
TL;DR: Long post about being true to yourself and not caring about what other people think blah blah blah sentimental crap.
P.S. I kinda posted in almost every topic you made because I love you now and I'm a clingy bish.