Wordpress security - login url and username

As I have serious problems with brute force login attempts into my Wordpress site I followed some recommendations from other forum members to change the login URL and limit the attempts (WPS Hide Login and Limited Login Attempts Plugins). I have less login attempts, but still a considerable number... I have two questions

1) How do the bots find the new URL so fast? Any other plugin or solution?
2) Some login attempts are with general common usernames. But I have 2 WP sites where they know my very unique username. How could this happen? And how to do better?

1) I'm not sure how WPS Hide Login works, but I'm a fan of 'Hide My WP' and it seems to do the job for me.
2) Have you ever posted articles under that username? That is a possible source. Another way bots and hackers get usernames is via user enumeration from /wp-json/wp/v2/users and other sources, which you can disable using plugins such as 'Stop User Enumeration'. But once a bot has scraped a username it's likely they'll just keep on trying with it.

Thanks a lot for your feedback...really appreciate it. I will give the Hide My WP plugin a try. Regarding whether I ever posted articles under that username... Yes, at least for one site(and I feel stupid not considering that). I will also give the user enumeration issue a try.