I had a confessor tell me that a Mortal sin is like an elephant in the kitchen. You know it’s there. I think that is true if your conscience is well formed.
Holy water removes venial sins. Also, at Mass, there are several opportunities for the removal of venial sins, the best–Jesus himself in Holy Communion. Also, you can receive an indulgence for reading scripture or going to Adoration.
Waiting is fine. But, if you are really troubled, I’m sure you can phone the priest and explain your desire.
We have lots of opportunities for confession at my parish; however, with my children and my hubby’s crazy work schedule, I often have to put off confession. So, I understand your desire. I think sometimes, God makes it more difficult to receive confession to increase your desire for it. But, that is my own speculation.