there is no more ‘public revelation’. That’s what was passed down to us from the Apostles, the Bible, and the dogmas of the Church.
All the stories about the Saints or miracles or people who’ve seen the Virgin Mary etc are called “private revelation”.
If a “private revelation” is accepted by the Church, Catholics are free to believe in it. I’m not sure how long it takes, but usually some of the clergy - priests, bishops, - examine the revelation and the person to make sure there is nothing against faith and morals, and the person really does live a holy life. Obedience especially is a sure sign, since the devil can’t fake that, cause it requires humility. The person who received the “revelation” should be obedient and submissive to the Church.
If you’ve had something potentially miraculous happen to you, try talking to a good priest or a spiritual director if you have one.
hope that helps…