There are indeed more thorough search tools you can use on a Mac.
Here is a thread with some tips for an extremely similar case (you might want to skip down to my second longer post, as the first covers easy stuff you’ve already tried). Probably no sense in going all over all of that anew, here, as nothing about any of this has changed since then. Spoiler alert: they found their work in the trash (which Spotlight won’t look into).