Why have you kept
Security updates disabled? A lot of 'security loophole'-killing and critical additions are done by the same.
I'm not much aware about the effectiveness of AVs on Mac though.
Consider adding "
HTTPS Everywhere" in Firefox.
Do you have an external storage? If yes, Apple's
Time Machine is a good tool, besides cloud, to backup files and make entire copy of system regularly. Though corruption or data loss chances look lesser in Mac, having backups is always an important safety practice recommended here, that can be useful at critical times (SSD drive failures or accidental deletion or Ransomware attack - yes there exist some for Mac).
Here's an interesting article on the 4 available modes of backup and the tools in case you would like to dig deeper.
*Make sure to disconnect external drives after backup, if not needed. There has been a slow rise in ransomware attack designs targeting Time Machine backups. Chances, you know!