I would point you back to the words of Christ, St Paul (1 Cor 11), and the many popes and doctors of the Church. The Church was given authority by Christ and the Church has held the truth of transubstantiation from the beginning (though the word took a while to define).
I would only say that neither you nor any other human being can prove it, and what difference does it make?
Is that you, Hilary? Just kidding. Getting punch-drunk from fatigue.
The question of authority is essential because without it we have no unity. We are mean to be one in faith (John 17:21). Please read the following prior posts on the subject of authority... it is important and makes all the difference.
On the Authority of the Church
More on the Authority of the Church
Even more on the Authority of the Church
The Church and Apostles were given specific authorities, many cited in this thread.
Plenary and arbitrary authority is only ascribed to any human or institution and claimed by Satan, as demonstrated (pun!) in the Gospels:
Matthew 16:23
But he turned, and said unto Peter, Get thee behind me, Satan: thou art an offence unto me: for thou savourest not the things that be of God, but those that be of men.
Mark 8:33
But when he had turned about and looked on his disciples, he rebuked Peter, saying, Get thee behind me, Satan: for thou savourest not the things that be of God, but the things that be of men.
I looked up the words of Paul, and they were:
1 Cor 11:24 And when he had given thanks, he brake it, and said, Take, eat: this is my body, which is broken for you: this do in remembrance of me. 25 After the same manner also he took the cup, when he had supped, saying, This cup is the new testament in my blood: this do ye, as oft as ye drink it, in remembrance of me. 26 For as often as ye eat this bread, and drink this cup, ye do shew the Lord's death till he come.
These verses don't seem to suggest transubstantiation, rather, they suggest a memorial, a way to remind ourselves and proclaim the great sacrifice made for our salvation. It does not seem to suggest failing to take the supper or to believe in transubstantiation leads to damnation.