What is Mortal Sin?
Am I Forgiven If I Don't Go To Confession? Yes and no depending on the circumstances. This is what the Council of Trent says in Session 14:
"...it sometimes happen that this contrition is perfect through charity, and reconciles man with God before this sacrament be actually received, the said reconciliation, nevertheless, is not to be ascribed to that contrition, independently of the desire of the sacrament which is included therein. And as to that imperfect contrition, which is called attrition, because that it is commonly conceived either from the consideration of the turpitude of sin, or from the fear of hell and of punishment, It [the council] declares that if, with the hope of pardon, it exclude the wish to sin, it not only does not make a man a hypocrite, and a greater sinner, but that it is even a gift of God, and an impulse of the Holy Ghost, who does not indeed as yet dwell in the penitent, but only moves him, whereby the penitent being assisted prepares a way for himself unto justice. And although this [imperfect contrition] cannot of itself, without the sacrament of penance, conduct the sinner to justification, yet does it dispose him to obtain the grace of God in the sacrament of Penance."
Simplification: If someone has perfect contrition (sorrow out of love for God), he can be justified without partaking in the sacrament of penance, if and only he (1) repents, and (2) desires to partake in the sacrament, meaning he plans on going as soon as he has the opporunity. For example, a person is forgiven if he commits a mortal sin, and after, shows perfect contrition and repents and plans on going to confession as soon as possible. But one is not forgiven if he does not show perfect contrition and does not plan on going to confession as soon as possible. Since he does not plan on going to confession, he does not repent.
Conclusion: To be forgiven, you must have the (1) desire to partake in sacramental confession as soon as possible, (2) have sorrow for all mortal sin out of love for God, and (3) repent.
If you have any questions regarding this topic or anything mentioned in this article, feel free to read my articles titled "Do I HAVE to Go to Confession?", "What is Mortal Sin?", and "What exactly is the Sacrament of Confession?"
God bless.