With all his heart, Jesus wants to forgive people their sins. This is the ultimate reason why he died on the cross! To forgive sins, Jesus instituted the sacrament of reconciliation, also known as confession.
The Apostles and their successors (bishops and priests) were instructed to forgive people their sins on behalf of God (Jn. 20:21-23). When a priest absolves you of your sins (absolution), you are truly forgiven by God. So there is no reason to doubt whether your sins have been forgiven. In the #DeoQuest app you can find the words of absolution in many languages.