I think this is how I always felt but only now I feel confused

I've been questioning myself for a while, but only now I've decided to write in some kind of forum and look for some answers...

I'm 26 and I've been thinking maybe I was asexual (or somewhere on the spectrum anyway) a while after I was forced to befriend a sociopath wannabe for months (long story short, an aunt wanted to find me a boyfriend, stuck me with this huge idiot, and then I spent months trying to get rid of him). That was not a real relationship, but I guess it was abusive enough to influence me in some ways (now I overreact to strangers that write me on Facebook and Instagram for example).

I found the definition of asexuality a couple of years ago, I think, and I immediately thought I might be somewhere on the spectrum. At first I thought maybe I was still too influenced by that bad experience, and that it might have been just a phase, but the more I thought about it, the more I realized that I might have always been this way. From what I can remember, I'd always wanted a romantic relationship with someone, but I don't think sex was ever in the picture. Another curious thing that I noticed is that sometimes the romantic relationship was retroactive: I thought about someone that I knew in a romantic way, but only after we didn't see each other anymore (like, we stopping going to school together). I don't know if this even makes sense, but it's kinda hard to explain.

This last thing made me think maybe I was demisexual, because I only seemed to show some kind of interest towards people that I already knew. I realized that this worked also with celebrities: I only feel somehow attracted to the ones that mean something to me, or for example actors who played a role that I liked a lot. This makes me remember when all the girls in my high school loved this male model that I found quite ugly: he was kinda good looking, but he meant nothing to me, so I was kinda indifferent.

And then a few months ago I started a training course in order to start a new job, and there were a lot of parallel classes for this training. I remember after the first day a girl from another class asking me: "So, are there any cute boys in your class? Is there someone who you'd have sex with?" And this question left me speechless. I mean, that girl seemed like one who always goes to parties and likes to have sex with a different guy every day, but my first reaction was: "Is that how most people really think? Am I not normal?" and I think I answered something along the lines of: "No, well, I don't even know them!"

So yeah, this is what led me to this subcommunity and to me writing this post. It's not too late to learn something new about myself, and I'd love to find someone to talk to, who could help me figure myself out and stop overthinking this.