Maybe too late to give you any helpful advice, but setting up Advanced Protection may make sense. You need to buy at least two (preferably three) YubiKeys and the password plus any of these keys allow you to login to your account. Nothing more, nothing less. Costs a few bucks, but at least the auth flow is very clear.

Another thing you can do is to wait for a week and see if anything changes. Having the session last for more than a week may give you more options in passing the challenge.