DAE not like the idea of having sex because it feels too "adult"?

I 19f am a virgin and I'm NOT asexual. I've always thought about the first time as something to look forward to with a long term partner one day.

I like making out with the person I'm dating, petting over clothes, grinding or whatever and that's all I've been comfortable with.

However, when I really think about it from reflecting on previous relationships I feel like it would feel like some out of body experience, to ACTUALLY have sex, as if I'm watching myself do something, but it's not really me.

I'm obviously not a child nor do I lack the proper intelligence, but it gives me extreme anxiety to know that day will come and that I'll feel not "grown up enough" for it. Even tho I AM a grown up.

The idea just sounds so unreal and dissociating, like I'd still feel like a child and innocent and I'm doing something so the complete opposite for the first time.