After looking into this, it seems based on
https://academic.oup.com/chemse/article/36/1/9/442551 that you can be unable to smell it in your own urine either 1) because your body doesn't produce it OR 2) because it's there and you are simply unable to smell it.
Unfortunately, I guess the only way to be sure (which would be kind of gross) would be to see if you can smell it in urine produced after eating asparagus from someone else who
can smell the asparagus scent in their own urine. Or, I guess, just sort of see if anyone seems to notice it after you've been eating asparagus.
If you're not sure it might be safer to assume it's because you just can't smell it and avoid eating asparagus.