You shouldn't label yourself as asexual right away. If you have a low sex drive, it is possible your testosterone and/or other hormones took a nose dive. The same goes for women who have no sexual desire. It is often due to poor dietary choices and lifestyle which deplete the body of vital nutrients necessary to produce hormones. Conventional labwork ordered by general practitioners doesn't give much of an insight either.
This is a very common problem and naturally nobody talks about it openly due to its nature. I see it all the time with couples trying to get pregnant. Oftentimes, frequency is a huge problem as the husband cannot even handle more than once or twice per week(their norm is once a week or once every 2 weeks). That is very low, but generally, people have become accustomed to that and say it is normal for married couples. It isn't. I'm only bringing this up to illustrate my point that sexual desire is declining for most people. There are exceptions and those exceptions typically happen for very very young folks or very healthy folks.
There's also psychological issues that may have something to do with the lack of interest. Pornography exposure, bad relationships, relationship trauma, low self esteem and the list goes on.
I say this mainly for everyone reading. Just because you don't have desire doesn't mean you are asexual or homosexual or weird. The answer can be very simple, but you'll have to take an interest in your health to find your solution.