I'm glad you've found useful feedback here.

Sometimes growing up surrounded by unhealthy relationships can give a person a clear idea of what they really don't want. That's a start.

It's not impossible for a person to fall in love with someone else whose appearance didn't initially create any attraction. It's been known to happen.

Here's where I sense some confusion in what you say: you say you don't find your S/O physically attractive. You also say you don't think you would want sex with anyone because you are "asexual." Or that's how I took it. (Maybe I'm mixed up.) So, if you met someone you found really physically attractive, you still would have no interest in sex with that person?

By the way, wanting to have sex with a person is not totally dependent on physical beauty. Being in love with someone is not totally dependent on finding a person physically beautiful.

I suppose anyone can conjure up an image of a fantasy person who would have every beautiful feature that might appeal to this person. People differ in how important that all is. You may have to go through a few transient relationships before you work out what you most need in a significant other. That's okay also, IMHO.

Sooner or later, the aging process tends to rob everyone of physical beauty. Lots of people stay very much in love, despite that. That may be something you've never witnessed. That may dim your appreciation of what is possible between people.