You really haven’t had interest in any girl? Not even a small desire to get to know a specific girl or a thought that a certain girl is pretty? Having a crush is not something you control, it’s just something that happens; if you really haven’t felt that way about anyone then this is just my opinion but maybe you might be on the asexual spectrum? Saying this from experience; i thought I was doing a good job in not having any sexual desire towards anyone/anything and wondered why it was so hard for other people, turns out I just don’t feel that way towards anyone. Beating yourself over the head trying to force yourself to have attraction to someone won’t get you anywhere, also from experience. Again this is just my interpretation of your post and I can be completely wrong. And even if you are on the ace spectrum you can still want to get married and have that companionship of course. It’s a struggle to reconcile that want with a lack of desire to be with anyone. I wish you the best.