I am no expert either but I found this article really interesting: https://www.wordfence.com/learn/how-passwords-work-and-cracking-passwords/ near the bottomIn How Crackable Is a Given Password is an idea of how password strength affects the time taken to crack - you will be very surprised how much difference 12 characters makes over 9.:
If you now expand the length of your password to 12 characters, you have 72 to the power of 12 or 19,408,409,961,765,342,806,016.