Being asexual is easy... For me it was at least...
Recognizing, that there is types of attraction, helped me to understand my sexuality.
I desire to be close, as in cuddles, kissing etc... but i at times, am as platonic as just holding hands can be to much for my sensory abilities. It makes finding a partner hard, as i can be "hot/cold" my partners have said..with touch.
I was able to, with a lot of research, see that one can be Romantic to any gender, without desiring to be intimate.
For me, its a Hetero-romantic ( attraction to dating Men).
And the rare beyond rare Gyno-romantic ( attraction to women).
Then there is your libido. which for many Aces, is there and responds to things like sexual stimulating and images that seem erotic. to me, this is a physical only response, and most bodies react to sexual touch even if you are not sexually desiring it. ..
Then finally there is your Sensory stimulus... For me depending on the ability to enjoy sex, depends on my partner's ability as well. And personality. If he cares enough to ensure i am happy without sex being involved, then thats great! i hate the messy clean up and semen is gross on me/in me. But if sex is ultimately desired between me and my partner, and i trust in them well enough not to be sick/cheating. Then sex might happen.
As a whole, I never desired sex like most, nor did dating the normal way, interest me either. Men never looked at me when i was growing up, despite being Hetero-romantic. I simply repulsed anyone because i seemed just Non interested.
To end the post, I think Asexual, boils down to more then just if you had sex and liked it before and now you dont... Or you never masturbate and that is fine with you.. Or even as simple as, besides no medical issue causing it, you just dont desire it anymore.