Okay, I have so much to say on this.
1. I want to punch you in the face for playing that whole "Oh I'm kind of awkward, I'm not so cool" card. You can't just keep putting out that energy. Regardless if you have low self-confidence or not, you don't go around saying that to people. That a) indicates that you begin with the assumption that they care about you, a very personal thing that instantly discomforts many people and b) reinforces your own image of yourself
2. Like someone else said, you probably are having an identity crisis and don't know who you are really. This is fixed with time for the most part.
Now, the root of many teenagers problems is confidence and self-confidence. The best thing to do would be to pull the weed out by its roots so to speak and gain confidence. The best way to do this? I'd recommend working out dude. Nothing will boost your confidence more than a great body. When you look great and feel great, it's pretty damn hard to feel not great about yourself. (If you do decide to work out, make sure you focus on strength training, eat plenty of protein and food in general, and focus on freeweight exercises)
Second comes your social life, it sounds like you really need to get away from this group of people and this girl in general. People think that they need to have everything in common with someone in order to be their friend or more. That's really not true, and it's been shown in college studies. It really comes down to you being a cool, calm, interesting, and confident person.
But seriously dude, get away from this "pack leader" guy, I know exactly what you're talking about. I've had that experience before. And the girl? Why would you want a girl who's another one of the brainwashed, go with the flow followers? Get out of there man and meet other people. Honestly, this is going to sound stupid, the best way to meet people is just to say hi to whatever random person and be relaxed and YOURSELF. If you get a new seat in a class or whatever, say hi to the people next to you, talk to them a little. Don't make yourself out to look like some kind of weirdo who's needy for socialization, but talk to new people at least.
And most people don't want to face the fact, but the key to being confident and interesting is to live an interesting and confidence building life. Whatever that takes, you have to strive to do it. I wholeheartedly believe that working out would help you a ton, I wish I would've started working out sooner.
Really the key to becoming the best version of yourself is to imagine that your friend has your exact same problems and is asking you for help. What advice would you give him then? Follow that advice. Live your life like you're the hero of a movie. The hero starts off small, gets shit on every day by everybody, he's a nobody. But he always ends up turning it around, getting the promotion, getting the girl, etc. Live your life like you're that hero, do what it takes be successful.
I'd highly recommend you listen to the Joe Rogan Experience podcast on iTunes, it's an amazing comedic podcast that would really help you with your problems, it's helped me and many others. Seriously, download a few and listen to them while you're playing Dwarf Fortress or something.
(
https://itunes.apple.com/us/podcast/the-joe-rogan-experience/id360084272)
Best of luck and I love you dude. I've been in your place before and can completely sympathize with you, you'll make it out fine.