Oh no, you’re not being rude at all!
It’s kind of difficult to explain how I “found out” I was asexual, because it wasn’t so much of a discovery process as a “okay, I don’t feel sexual attraction to males or females or anything really for that matter, and I’m just very adverse to the idea of sex and cannot fathom it beyond practical value (ex. passing on genes, evolution, etc.) so maybe I’m asexual”
As I mentioned in a previous post, asexuality is a spectrum, and there isn’t a one-size-fits-all for it.
Hope this helped, even if only a little bit.