I no longer build or maintain WordPress websites.
Who could maintain your website?
If you’re a US nonprofit, I recommend Valet.io.
Hosting
I recommend either WP Engine (not cheap, but very secure) or Siteground (cheaper but still reliable and well-featured).
Automated backups
Ideally your website hosting company does daily backups. If not, you could automate the task using a well regarded and reliable WordPress plugin called Backup Buddy. Backup Buddy backs up everything including your MySQL database, WordPress core files, theme, uploaded images and documents; the resultant compressed file is ready to download and can also be automatically saved to the cloud.
The WordPress Community
Check out NTEN’s WordPress Community forum which supports non-profits who use WordPress.
I used to volunteer on the WordPress.org support forums – see the WordPress questions I’ve helped to answer.