The Trent Catechism puts it this way…
After saying how awful it is to conceal some sins (which is not your situation) it is taught that the entire confession must be repeated, because it was sacriligiously done, the following is said, in regard to “Sins Forgotten”
But should the confession seem defective, either because the penitent forgot some grievous sins, or because, although intent on confessing all his sins, he did not examine the recesses of his conscience with sufficient accuracy, he is not bound to repeat his confession. It will be sufficient, when he recollects the sins which he had forgotten, to confess them to a priest on a future occasion.
Then it says that we should be diligent in examining our consciences, so as to not forget to confess mortal sins.
If you had not remembered the sin, then it would be ok, but since you did remember it, go on and confess it. But don’t be scrupulous, trying to remember all sorts of things. God’s not “out to get ya.”
