Then, after 2 months, I tried logging in and suddenly it worked.
A few hardware security keys will probably prevent this problem for you. I'm wondering why you didn't consider getting them after you had login problems before.
I use a seriously backed up password manager that I have means to access from anywhere, and the only thing I have to worry is that I'd forget my really complex password to access it, because it is unfeasible that I'll lose all my devices where it is backed up and also an off-site backup of it.
With hardware keys, however, I constantly have to worry to keep them with me or in a safe place and not to lose them.
(my position is partially rooted in the fact that I happen to live in a country where you can easily have all your material possessions forcibly taken from you)
If you lose your hardware keys, you still have your other 2 factor options, so you are no worse off than your current situation.
The safest option is straight out of 1994: Sticky notes.
Security keys can get lost or stolen. If someone breaks into your house or office, they're going after something other than a sticky note in your desk.