This book would be of help to you OP. (I wasn't able to find an e-copy)
https://www.traditionalcatholicpublishing.com/confession-made-easy.html
Fructuosus Hockenmaier. Now I know what I'm going to name my next son, should I ever have one

(Don't laugh --- my wife could die, I could win the lottery, I'm not dead yet, and I could meet some sweet young traditional Catholic lass and have the mega-family that should be every Catholic man's ideal. Age ain't nothing but a number.)
But seriously. This book has a 1910 imprimatur. Modern Newchurch Catholics (after a fashion) wouldn't know the difference between mortal and venial sin if it bit them on the butt. I haven't read the book, never heard of it, but given the date of the imprimatur, I have to think large portions of it would fly right over their heads. They have some vague notion of "grave" sin, which term is so misused that it has come, to some of a more serious bent, to mean any sin at all.
I'd say just to find a traditional confessor, let him take you by the hand (metaphorically speaking), and go from there. Stick with one confessor if you can.