You shouldn't have been. Ever heard of binding and loosening?
Pope Bl. Pius IX in Apostolicae Nostrae Caritatis:
"Indeed We have decided to offer the treasures of divine gifts, whose dispensation the Most High entrusted to Our care, so that your faithful may pray with more fervent love and more abundant fruit. For this reason, by the mercy of almighty God and trusting in the authority of His blessed apostles Peter and Paul, We confer, by the power of binding and loosing which the Lord gave to Us, a plenary indulgence of all sins as in a jubilee. This indulgence will be granted to all the faithful of your dioceses who accomplish the following acts within a three month span to be determined by each one of you and computed from the day which you decide upon. They must have humbly confessed their sins with sincere regret for them, and after being purified with sacramental absolution, they must have reverently received the sacrament of the Eucharist. They must also visit three churches designated by you or one of the churches three times and must say prayers there for the exaltation and prosperity of Holy Mother Church and the Apostolic See, for the elimination of heresies, for the peace and harmony of the Christian princes, and for the tranquillity and unity of the whole Christian people. Moreover they should fast once within the same period and give some alms to the poor. This indulgence can also be applied to the souls in purgatory."
There you go.
I don't think I can even understand all that, or figure it out. Maybe if Petronius Maximus would color code it, it would become clearer.
I offer every Mass I go to for the souls in Purgatory.
Just a thought: I've often thought it a little presumptuous to pray for the release from Purgatory those souls that are presumably there to atone for their sins. My reasoning (though maybe faulty) is that Neither I nor they would want to leave before everthing is accomplished.
The only situation I can imagine (in my finite mind) where prayer would release them is that souls would be languishing there after their purification is complete.