I didn't have COVID, and I also only had a day or so of fever after my J&J shot in June. My girlfriend had a similarly mild reaction, and we've both been tested regularly for various reasons, we're pretty certain that we haven't been infected.

I just got my recommended booster shot of Moderna yesterday, now I'm waiting to see how hard that will hit me.

There are no certainties, but I know that here you would also been considered immune if you had previously been infected, but not yet vaccinated.

Bad public policy unfortunately exists, same with the thing about not accepting the J&J vaccine as valid. It works about as well as the mRNA vaccines against hospitalizations and death, but with somewhat less efficacy against base infection, and of course a slightly larger risk of complications. That doesn't make it a bad vaccine, so countries not accepting it is completely insane.