Basic important doctrines such as the resurrection of the dead and the ransom sacrifice are explained in great detail in the NT. It would be astonishing if the Trinity was indeed the central doctrine of Christianity as the churches claim, and yet the teaching itself was nowhere explicitly explained in scripture. But I don't find a single statement anywhere to say that there are three persons in one God.
The Trinity is not THE central doctrine of Christianity. I know of no church that makes this claim. An important understanding yes, but central?
The incarnation and the deity of Christ -- that is central and (I believe, though I know you will disagree) is explicitly set forth in the scriptures (John 1:14, John 20:28).
Salvation by grace through faith -- that is central and explicitly set forth in the scriptures (Ephesians 2:8-9).
But the Trinity is something inferred. And though I believe it is true and is taught by he who "correctly handles the word of truth" (2 Timothy 2;15), it is not central. It is possible to be saved and not only not understand the Trinity, it is not even necessary (IMO) to profess belief in the Trinity, "for God has mercy on whom he wants to have mercy" (Romans 9:18). As the scriptures declare of God, “I will call them ‘my people’ who are not my people; and I will call her ‘my loved one’ who is not my loved one” (Romans 9:25). So, what is central is more what God believes with regard to us, than what we believe with regard to God. To that end the most important verses of scripture really are John 3:16-17 -- "For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life. For God did not send his Son into the world to condemn the world, but to save the world through him." No mention of the Trinity there, but there is enough mention of the
monogenes to send us on a search of the rest of the scriptures to help us to understand his nature. And when we do, we find that Jesus is the unique manifestation of the one and only God that no one has ever seen, "but
God the only Son, who is at the Father's side, has made him known" (John 1:18).
So, important, but not central. And while not explicity stated, those who read scripture allowing for God to be who he is and not how we determined him to be can see that the God is just one being, yet known to us in three persons.
The first of those declarations, that God is one, is central. The second of those, that God is known to us in three persons, is equally true, but is only important for those who are willing to let God be God and seek to know him as describe himself, rather than what we determine for him to be.
If seeking to know God is what anyone here desires, then be advised there actually is more than one way to do this. Many lives bear testimonty to the reality that one can know and worship the one God without the full insight into his nature and depth of understanding that the Trinity can help to provide. I don't deny it. Such a person will know God as one knows a set of facts. But knowing God in a personal way, knowing that comes out of a relationship with God in Christ Jesus and through the indwelling of the Holy Spirit provides,
in my experience, a deeper and more intimate relationship with the Father, than anything I experienced prior to coming to that awakening in my own life. If you seek that, I invite you to enter that journey through coming to entering into a personal relationship with God where you heart becomes his home. And not saying what will be true for you, but what I found was true for me, was that this relationship led me to experience the one God as explicated in the doctrine of the Trinity.
If you do not seek that, and are satisfied with the guidance you have received thus far in your life, then I do not condemn you, but ask God's continued blessing on you. I also encourage and applaud you in your efforts to be obedient to the revelation that you have. And ultimately I trust in God and God's mercy to effect in your life that grace which he can provide to be sufficient for that to which he has called you.