Should I re-confess sins if I think the confession might have been invalid?

I think I might have withheld a mortal sin on purpose but I don’t remember if I did or not.
Also I didn’t say the number of times I committed a mortal sin because I didn’t know that I was supposed to.

Without knowing you or the circumstances, I’d say it’s probably a good idea. The way I’d do it, is to tell the priest at the beginning of the confession that you think you may have withheld a mortal sin on purpose (which would be an additional sin). He can stop you if he thinks it’s not necessary to go on. If you are excessively scrupulous or have other issues, and this is a recurring sort of thing, a confessor might treat it differently than with someone else.

Honestly, if you remember a mortal sin that you didn’t confess you ought to bring it up next time you confess even if you didn’t do it on purpose. If you might have withheld it on purpose, then yes, you’ll definitely want to bring it up (as you wouldn’t have been forgiven it). If you know how many times you committed a sin (even approximately) then yes I’d make sure to bring that up too. If you haven’t confessed in a long while and don’t really know, then ask Father to guide you. Remember, every sin you don’t deliberately withhold in confession is forgiven when the priest says the words of absolution. God bless.

If you didn’t know it was sinful at the time, you can also explain that in confession. As to the number of times, you can just estimate…1, 10, 100, 1,000, to give the priest an idea of the frequency. Do an approximation to the best of your ability.

Unless a spiritual director has advised you not to, I think you should do this, but also might want to mention that you may have withheld a sin and are now confessing it.

If this becomes a recurring problem, you’ll need to see a priest outside of Confession to ascertain scrupulosity.

Next time you are in confession, ask for guidance about making a good confession.

Ask if you should “reconfess” certain sins, however, it is likely the priest would tell you to be at peace and trust that God forgave them.

While I don’t think the number is as critical, (we are allowed to say "several"or “many” or other descriptive a when we don’t know how many times), we are obligated to confess mortal sins forgotten in previous confessions. It does not mean you did not return to grace, but after remembering if you choose not to confess it is mortal sin.

If you purposely withheld a mortal sin while intending to do so, it calls into question if you really were sorry for your sins and can render your past confession invalid. God will not poor out his grace if you did not want it. Tell the priest if this and be prepared to confess ALL your mortal sins, including the ones from the last confession in their entirety.

So go and confess what you think you may have forgot and let the priest know about the number issue and follow his guidance.

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