Let's begin with those insecurities you seem to have. You know, where you think those people over there are having more fun than you. Where you ditch your conversation for another, because they look like they're talking about something more interesting. Well the truth is, the grass is probably no greener on the other side. The only reason they seem to be having more fun than you is because you've persuaded yourself that you're having none. You just need to get it into your head that you are the scene. It's your job to make sure you're having fun. You make the conversation interesting. You say something you think is funny. And if you're having fun, the people will come to you. You'll be the one they ditch their conversations for.
Just stop being insecure, okay? Do you ever wonder why some people seem to be more respected than others? People listen to them more. People want to spend time with them more. The only reason for that is because they're speaking up. They're not afraid to say what they want. You can't be respected if you don't say anything at all. You can't be respected for just saying what everyone else is saying. You need to make up the phrase. You need to be the one everyone seems to be quoting.
Everyone is people, and people are just people. Not one is much better than another. The only reason you might think that is because the ones that are confident seem to be better. The ones that aren't are secretly amazing, but don't get as much recognition, and that's okay if you're okay with that. But please have the confidence to hold your own, to have your own known personality that is ultimately you. We need a variety of people, and you are part of that vast variety. I know it's cheesy but be yourself, because everyone else is taken. If you say what you believe in or want to say, then you'll also end up surrounding yourself with people who genuinely like you, who you can make good friendships with.
Stop icing out people you don't particularly know too. It could be that girl who's always on the bus. Or that guy who sits near you in maths. Or that girl who's always waiting for her parents in the same spot as you. Just say hi to them, talk to them, even if they have some kind of reputation, whether they're "undesirable", "weird" or "really popular". And if you like them, well start saying hi to them whenever you see them. That's how friendships are developed.
I know it's more difficult than it sounds. Speaking up can be hard in certain situations. Sometimes you really want to say something just to please the other person, or make them like you better, even when you don't believe it. And no matter how simple it sounds, saying hello can be the most difficult thing in the world.
But here's a tip...
Just stop caring.
My current lock screen on my phone says "You're at your best when you don't give a crap." And it's true. If you don't care what they think of you, saying whatever you want is easy, giving your honest opinion is easy, and saying hello is the simplest thing in the world.
The key to being confident is to live for yourself. You're the one having the best time. You're the one who thinks this and feels like saying it. You're the one who doesn't care what she'll think of you when you tell her you like this singer, or you think the guy she likes is ugly. You're the one who wants to get to know her, not the other way round. You don't care what she thinks of you. You just want another person to talk to.
And the truth is, if you let them see who you are, if you let them judge you for speaking up rather than not saying anything at all, they will probably like you. They certainly won't hate you.
If you decide to stop feeling judged and invite people over to your place, or have a party of your own, you'll end up having fun. Carry your own. You're a person, they're a person, you're just as important as all of them. In fact, you're more important, because you're you and you most definitely care.
The key to confidence is to put yourself up on that pedestal.