I was Catholic. All of my extended family is Catholic. Some very devout, some not very much. And I'll tell you what impact Catholicism has had on my family so far: false security, spiritual conformism, religiosity, idolatry, and superstitions. The fruit of the Spirit? Nope, nowhere to be found. But that's only my observation. I don't believe Catholicism teaches the true gospel because they added so much to it that the message of the gospel has been blurred and watered down. In other words, it's not the gospel of Jesus Christ. Sorry if this sounds harsh, but I've seen the fruits of Catholicism and it saddens me.
May I ask why you are considering becoming a nun? I don't think it's biblical.....I mean, we are called to reach people from all nations and I don't know how you would do that if you don't ever get out of a building.