I’m not sure that the essence of repentance is being able to list of all your sins to the Lord.
Obviously, it is crucial to recognize our specific sins, confess, and repent.
But it seems to me that we also have to recognize before the Lord our sin of not being able to see all our sins.
We need to cast ourselves on his sheer mercy. Yes, confessing what we know, but also asking forgiveness and mercy — and then sanctification — for the sins we are not aware of.
(Which may be the most substantial arena of sin!)