Were there really only twelve apostles? I've been researching about the apostles and found historical documents that show there were more than 12 but 12 + 7, including women. This information was included in non biblical historical documents. In reading the bible, the number twelve is highly important to jewish readers as it represents the twelve tribes of Israel. My question is have the gospel writers focused on the number twelve to keep in line with the hebrew books? Or could there have been more than twelve? It seems logical to not limit his number to twelve, in order to spread the word as far as possible.
Different books of the Bible use the terms apostle and disciple in differing ways. The word disciple means a follower or student of a teacher, while the word apostle means a messenger or ambassador who champions a particular cause.

Initially, the term "apostle" was used to describe the early followers of Jesus. There were specific requirements to be called an apostle, some of which were, the chief of which was that they had to have seen him after his Resurrection. Additionally, the apostles were the foundation of the early church, after Jesus, the chief cornerstone. So the "apostles" were limited in number, but not to only 12 (a disciple, however is a much broader term. A disciple is any follower of Christ, and as such there are millions of disciples today).

However, there is a common convention of a difference between "apostle" and "Apostle", with "Apostle" denoting the those specifically appointed by Jesus as apostles (the twelve, along with Paul). So there were the Twelve, but these were set apart by Jesus as his closest companions during his earthly ministry, and not an artificial distinction posed by the writers of the gospels. So depending on your definition, there might be 12 apostles or several hundred (see 1 Corinthians 15:6)