Venting - I got a girlfriend?

A friend casually asked me out and we decided we'd take it slow. We aren't lol. I've never dated before and I just want to do this right and make it last. They're supper flirty and I suck at reciprocating or at least expressing my appreciation. I'm worried they're on a high and are going to come down and leave me the second they snap out of it :( this is especially hard because I've been on a back and forth about being aeromantic for a while now, and I've communicated this to her  before she asked me out. She's going pretty fast and I'm scarred it's exaggerated; they're texting me constantly, flirting a ton, complimenting, "thinking about you" texts. What if we slow down and she gets bored of me?? I can't even say why I 'love' them, they're just the same person to me, nothing changed. I'm scarred but I know I wanted to start dating eventually to gain experience and figure some things out... Am I an asshole playing with her feelings???