Maybe the following will help:
Paul seeks our Cephas separately after the road to Damascus incident (3 yrs after): Galatians 1:18 Then after three years I went up to Jerusalem to visit Cephas and remained with him fifteen days.
Paul heeds a revelation to him and seeks out and submits himself, his gospel to the Apostles…Galatians 2:2 I went in response to a revelation and, meeting privately with those esteemed as leaders, I presented to them the gospel that I preach among the Gentiles. I wanted to be sure I was not running and had not been running my race in vain.
Take note…Paul had a direct revelation from Christ. Yet, from the two passages above, he goes to visit Cephas/Peter and submits himself to Peter. Gal 2: 2 states his purpose…to present his gospel/message to make sure it is in line with the Apostles and what they were handed down from Christ.
And in Acts 13, before his first missionary journey…he is ordained:
1 Now in the church at Antioch there were prophets and teachers: Barnabas, Simeon called Niger, Lucius of Cyrene, Manaen (who had been brought up with Herod the tetrarch) and Saul. 2 While they were worshiping the Lord and fasting, the Holy Spirit said, “Set apart for me Barnabas and Saul for the work to which I have called them.” 3 So after they had fasted and prayed, they placed their hands on them and sent them off.
Before Paul and Barnabas went on their first missionary journey, he submits himself to Church authority and are ordained by laying of hands. Then they are sent out to their mission. Paul, by the laying of hands, first becomes an Apostle, he gains apostolic authority, thereby, the Churches he founds have apostolic succession.
But if that is so, why wouldn’t others who have had visions of Jesus not be called an Apostle or have had Public revelation made known to them?
Jesus appearing in apparitions after Paul may have different purposes. Paul was called by Christ to bring the Gentiles into Christianity. But take note, before Paul went on his first missionary journey, he had to be ordained, as recounted in Acts 13.
And as the Gal 2:2 passage says, the revelation to Paul was not to go out by himself, the revelation to him was to seek, submit to an authority, and have his gospel assured that it was in line with what was revealed to the Apostles.
Think about his passage and how it relates to Gal 2:2:
from 1John 4…6 We are from God, and whoever knows God listens to us; but whoever is not from God does not listen to us. This is how we recognize the Spirit[a] of truth and the spirit of falsehood.