My friend,
This comes down to faith in the sacraments, and faith in yourself, that you be true to yourself and do what you know to be right. But do not forget, that unless it is the will of God that you never screw up (a rare gift from God in my experience haha), you will most likely screw up again. What matters is that you try to not sin…but you and I are fallen human beings and it is impossible without the grace of God. Just tell yourself that no matter what, whenever you sin, you will always CHOOSE to come back to the Lord and seek confession when necessary.
Personally, I view confession somewhat like taking a shower. If I was in a desert, and every week the Lord came to visit me (the Mass and the Eucharist) then surely I would want to clean myself up. This is why I recommend going to confession every 1-2 weeks. I do it because I want to be ready for the Lord at the Mass. If I mortally sinned, so be it, but even if I did not MORTALLY sin, then I still feel I should clean myself up. I think doing this, and meditating on why we go to confession, i.e. to be ready to receive Jesus in the Eucharist is good practice for staying in a state of grace.