@Gorgias, @Anesti33 that was kind of the idea, if the priest didn’t know any better the Confirmation was still valid (not sure meaning or how but beyond topic).
My point is if the priest doesn’t know the level of doubt in the person confessing, should still accept the person confessing… but even if you think about it deep enough even confessing you have doubts or confessing don’t believe in God would be a form confessing the truth and should be forgiven. (taken beyond the confessional but that too is a different topic)
Bottom line, you should always go to confessing… it will will help in many ways… even with doubts… there is a reason you’re confessing, there is a reason you care enough to know if it’s accepted… there is a reason you want forgiveness. Which is why, again, I ask the OP’er what do you really mean by just covering your bases?