Jesus literally said baptize in THE NAME (Singular) of the Father, the Son and the Spirit (Matthew 28:19).

If you do not see that as the trinity in the text, there is nothing I can do to help you.

FYI what Nicea did was to turn the doctrine WHICH WAS ALREADY THERE, into a creed. A creed that captures all the elements of the trinity particularly regarding Christ. Again, very clumsy summary of Nicea but point is it did not birth the trinitarian doctrine. It is clear in scripture per the few references out of many given in the article.