You are right to be concerned as we all should be.
God does punish even venial sins very severely. Look to Moses and because of his hesitating faith, was not allowed to enter the Promised Land. Deliberate venial sin is the greatest evil in the world next to mortal sin.
Catholics, myself included don't realize this as much as we should think on it daily.
During confession all that is required that you promise sincerely to TRY, not to sin again.
When you meditate daily on the horror of sin, it makes it easier to TRY never to sin again. We can't promise we will never sin, because we just can't make that promise.
If you are sincere in making this promise to TRY never to sin again, then all your sins will be forgiven in confession. That is my understanding of the sacrament.
Don't give into the :devil2: saying, "you can't do that". . . .promise never to sin again.
Many of our sins may not be sins but reactions to something, or what someone says, that is why, even posting here, we should take a deep breath, and think before we post.
Even so, if only a reaction, we have an obligation to stop this bad habit and develop good posting skills.
Guilty your honor! :judge: (speaking of myself)