So I feel like I should go to Confession, but I don’t know what specific sins (as far as I’m aware, I’ve committed no mortal sin) to confess to. Am I allowed to just say “I am sorry for all the sins I have committed in my past life” and recite the Act of Contrition? Thank you all ahead of time!
Baltimore Catechism No. 3
Q.
782. What should one do who has only venial sins to confess?
A. One who has only venial sins to confess should tell also some sin already confessed in his past life for which he knows he is truly sorry; because it is not easy to be truly sorry for slight sins and imperfections, and yet we must be sorry for the sins confessed that our confession may be valid – hence we add some past sin for which we are truly sorry to those for which we may not be sufficiently sorry.
Q.
783. Should a person stay from confession because he thinks he has no sin to confess ?
A. A person should not stay from confession because he thinks he has no sin to confess, for the Sacrament of Penance, besides forgiving sin, gives an increase of sanctifying grace, and of this we have always need, especially to resist temptation. The Saints, who were almost without imperfection, went to confession frequently.
Catechism of the Catholic Church
1458 Without being strictly necessary, confession of everyday faults (venial sins) is nevertheless strongly recommended by the Church.59 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:60
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.61
1855 … Venial sin allows charity to subsist, even though it offends and wounds it.
1863 Venial sin weakens charity; it manifests a disordered affection for created goods; it impedes the soul’s progress in the exercise of the virtues and the practice of the moral good; it merits temporal punishment. Deliberate and unrepented venial sin disposes us little by little to commit mortal sin. However venial sin does not break the covenant with God. With God’s grace it is humanly reparable. "Venial sin does not deprive the sinner of sanctifying grace, friendship with God, charity, and consequently eternal happiness."134
While he is in the flesh, man cannot help but have at least some light sins. But do not despise these sins which we call “light”: if you take them for light when you weigh them, tremble when you count them. A number of light objects makes a great mass; a number of drops fills a river; a number of grains makes a heap. What then is our hope? Above all, confession.135
It is true, there is always something to confess. Even if you just remember some tiny venial sin, mention it and state that for all those sins which you may have forgotten, you wish to ask for forgiveness. 
I hear that statement about JPII, but he had enormous responsibilities and everything he said had import worldwide. This is not the same as a grandmother with a part-time job who plays a lot of Candy Crush.
No doubt I’m missing something, but can’t figure out what.