Your Trinitarian beliefs are demonstrably heretical, and your description of the Gospels as OT are equally as false. Do these beliefs come from you or are they taught by your cult?
When did Jesus say he was going to institute a NEW TESTAMENT? That should answer your question of the period of time covered by the gospels
And by the way, I learned this fact from a Mennonite professor of theology in a Bible Survey class. It is an accepted fact by Christian Theologians