(oops, accidentally reposted that instead of replying)
one relay wouldn't necessarily know about all your followers. and you might even have followers on relays that you're not directly connected to.
Discussion
figuring out exactly how far your posts is reaching is what my https://nrcheck.tigerville.no tool does. i don't publish to all the relays that are listed there for my posts, but i might still have followers who use them.
