I think that sometimes, but I'm on a different scale cuz I'm with someone, and I often freak cuz it might be my last, and I don't like the idea of it cuz there is so much more shit to do, not as in sex wise, but more to learn about people in general... everytime you meet someone, and actually make a connection, you learn something, subconsciously even.
Anyway, going back to you, there isn't really advice I can give you. Just go with it. Whatever comes you way
Why fear something that hasn't even begun yet.
^^^I say that to myself all the time.
As for longing for someone, maybe you need to talk to individual people more... talk to that chick or whoever and talk about this stuff, or something as "deep" as this. They won't judge you. Girls LOVE that shit. They LOVE getting opened up to, they feel priviliged. I'm aware of this and I still buckle at any guy that gets deep and meaningful with me. I know guys don't often do it. And if the girl don't like it, its an easy retreat, say you trusted them and throw a good guilt trip.
I don't particularly think you have any social problems either, nothing too mainstream emo, I mean, i've seen 19 year old boys have a huge quarter life crisis at me and this seems tame to me.
Seriously, chill, like the cool and calm guy you are and go with the flow of things
You've got so much time to filter out the crap girls, or even play around with them before you realise what kind of a girl is best for you.
You won't be the last person to love/like/have a connection with Catherine and she wont be the last to love you, I mean, fuck, you know yourself this amazing girl is out there. Just not the time, you know?
And if you do meet her "too early" and its the end of all your relationships, well, if youre actually thinking that sort of shit during that relationship for an extended period of time, then i guarantee it WONT be your last.
Traditionally speaking, YOU will be the one to pop the question of whether its going to be your last relationship, so when it DOES happen, you would've done a lot of thinking
hence, don't worry.