Stopped reading at “storing my passwords on a db”. Even if you encrypt the data, is it not just plain better to use a generative algorithm for passwords instead that needs no cloud? Why would you even introduce the vulnerability yourself of storing passwords somewhere in the first place? Keep it simple, you don’t want to over-engineer yourself to death, especially if you are actually downgrading your security by building too far ahead of what you actually need.
Once you master password gets leaked, attackers would also need to know: