I'm going to talk to you like I talk to one of my children. It seems to me that you never had a good formation for Confession as a child, and now you're dealing with this as an adult.
There are 5 things needed to make a good confession.
1. Know your sins
2. Be sorry for your sins.
3. Make up your mind not to sin again
4. Tell your sins to the priest
5. Do the Penance the priest gives you.
That's it. Make a good examination of conscience. NOT over and over. ONE good honest one.
Then, ask for the graces to have a true sorrow for your sins. This does NOT mean tears coursing down your cheeks every Confession! The simple desire to have true sorrow--sorry because we've offended God--I repeat, the desire is enough.
Have a firm purpose of amendment. Not an "Oh, well, I'll just confess it so I can go to Holy Communion, but after confession I'll go ahead and keep stealing those candy bars (or whatever)!"
Tell your sins--Now. If you forget any...absolutely any...they are forgiven. The important thing is to confess ALL mortal sins. I think this is where you're getting hung up. If you have honestly forgotten one in confession, it's still forgiven. If you remember it later, it's ok to still go to Holy Communion--it's been forgiven, but you HAVE to confess that you forgot one at your next Confession. But you didn't just make a bad confession! If you have the honest will to confess all mortal sins, then Our Lord sees that. He knows your true intent was to confess. Since you're worried that you're pushing them out of your head, then you probably are NOT.
And of course, do your penance.
If you fulfill all those, you've just made a good Confession.
I think that your problem is you tend to over think things. Remember, in order to be a mortal sin, it has to fulfill 3 conditions. 1. Serious matter 2. Full consent
3. Done willingly (deliberate consent)
Serious matter--killing a man vs punching someone? Extorting thousands of dollars vs pennies of interest on a savings account?
You see?
My main advice to you would be to try to be more child-like. Children are so simple and innocent; you've got to stop this! Of course the devil doesn't want you to go to Holy Communion and tries to trick you into thinking you've made a bad confession.
As someone else said, you must TRUST. Pray for that grace!
I would highly reccommend the book written by Mother Mary Loyola. It's titled "My First Confession" and is written for 8-10 year olds. It explains the purpose of Confession and tells you how to make a good one. It's excellent; I enjoy reading it every time I teach my children! Very quick read; you might want to look into it.
Good luck! My prayers are with you. And go to Holy Communion today! If you're afraid you've made an unworthy confession, you probably just made a good one. That devil is very very sneaky.