Never be discouraged.
God has great Mercy when we ask for it. (Thank goodness

)
All of us are sinners in one way or another.
Here is a link to good examiniation of conscience.
fathercorapi.com/Examination-of-Conscience-Making-a-Good-Confession-W13C85.aspx
Confession at least once a month is very helpful in our struggle against sin, as is daily prayer.
Some people go more often.
CCC - " 1458 Without being strictly necessary, confession of everyday faults (venial sins) is nevertheless strongly recommended by the Church.
Indeed the regular confession of our venial sins helps us form our conscience, fight against evil tendencies, let ourselves be healed by Christ and progress in the life of the Spirit.
By receiving more frequently through this sacrament the gift of the Father’s mercy, we are spurred to be merciful as he is merciful:
Whoever confesses his sins . . . is already working with God. God indicts your sins; if you also indict them, you are joined with God. Man and sinner are, so to speak, two realities: when you hear “man” - this is what God has made; when you hear “sinner” - this is what man himself has made. Destroy what you have made, so that God may save what he has made. . . . When you begin to abhor what you have made, it is then that your good works are beginning, since you are accusing yourself of your evil works. The beginning of good works is the confession of evil works. You do the truth and come to the light. "
Missing Mass on Sunday and Holy Days of Obligations through our own fault is a Mortal Sin, that must be confessed prior to receiving Holy Communion.