Take some time (a few weeks if necessary) prayerfully preparing for your confession. Make a list if that will help you (and after 10 years, I would recommend doing that.)
Remember as much as you can. Do not omit venial sins; you are not required to confess venial sins but if they bother your conscience, cough 'em up: all sin may not be mortal, but it’s ALL poison. When you have taken care to examine your conscience, and have remembered everything you can remember, and have confessed it simply, modestly and completely – without holding anything back, without hedging, without mincing words – and with the INTENTION of confessing everything, then what you have not confessed will be absolved along with the rest. Be at peace. Should you later recall a mortal sin that you forgot, mention it at your next confession.
Oh. And remember, if the Church thinks something is a sin, and you do not, that does not make it a non-sin. It means that your conscience is insufficiently formed. It mitigates your responsibility but it does not diminish the objective sinfulness of the act. Coming to confession says that you are prepared to accept the authority of the Church.
If this sounds too hard, ask Jesus to make this confession for you. He will not disappoint.
Your very desire to come to confession is a great grace. God be with you.