Well the universe is big and big.... If we are not in the center of the Milky Way, then it proves to me that we are not the center of the universe...
It proves no such thing. You have a curious level of certainty, about something for which science has no answer. Why is that? Would it be buried hostility regarding the religious answer to the question?
Einstein put an end to the debate. The “center” is wherever you wish it to be.
The center of the Universe is unknowable, since the extent of the Universe is unknowable, except of course to know it all atheists, then it is where ever they say it is.