I noticed that I didn't have any interest in sex when I was in middle school but I assumed I was a weird straight person. I knew asexual was a thing but once my mom found out I identified as it and told me I wasn't and that turned me off from exploring the possibility of being queer for years.
I was almost 15 when I finally started coming around to the idea that I was asexual. Oddly enough after I identified as ace again I became more open to the idea of having sex. Maybe I'm demi or just a sex favorable ace?