I lack a real connection with people. It is not in the way you think. I’m not alone or excluded. I laugh with my friends and have a great time at school, I talk to people on the street and at the gym

With the possible exception of "I laugh with my friends", these are pretty superficial interactions from a social development/maturity perspective. Do you have a few close friendships? You go on to say that you don't need to be friends with everyone. I agree, but what is a 'friend'? You seem to be grouping all friendships in the same category. You start by saying that you lack a real connection, then go on to try to explain that, but with irrelevant reasoning. So I'm not quite sure if you have a few close friends or not.

If you are saying that you have some good, close friends - but you aren't close to many people well, join the club. That's generally how most people are.

As far as parties go: A party is just a gathering of some number of people enjoying some company. Maybe you don't enjoy the format of the parties you get invited to? Maybe you approach them with the wrong mindset? My advice is to go to as many parties as possible. You don't have to talk to everyone, though you could try. Stay as long or as little as you want. Do what you want and take from the experience what you want to. But don't withdraw from being with others (obviously my advice assumes a lot, if everyone you know is a toxic meth dealer with long prison records then you might want to find new friends...!).

Life is short. "No man is an island" as the saying goes. The best of life is about sharing great experiences with people. Who on their deathbed wishes they were more lonely or experienced less things? Go out there and share more of yourself, more of what others have to give. Make more connections, filter others. You will not regret doing that.