All it takes is one.
Unless you have a hearing test BEFORE the noise exposure, you can't tell if your hearing has been damaged.
Before taking up shooting, my hearing was much better than normal. I have some interesting equipment in the lab where I work, and I was able to verify that I could hear frequencies way up past what is generally considered "normal."
Even though I have always worn hearing protection, exposure to shooting noise and other noises has degraded my high-frequency hearing considerably.
BTW, plugs are not as effective as muffs, regardless of the NRR number. A significant amount of noise is transmitted into the ear canal via the mastoid bone behind the hear. I used to shoot on indoor ranges using exclusively plugs and I suspect that's the major reason I've experienced so much loss even though I've always used protection.
These days, when shooting outdoors, I wear muffs. When shooting indoors, I wear plugs AND muffs.
And there's no blaming this on genetics. None of my parents or grandparents have experienced significant hearing loss with age.
With today's electronic hearing protectors, there is no excuse for not wearing hearing protection.