Yes it should be no problem to prove the website is yours.
Did you maybe click a wrong checkbox because Google now questions that you are the copyright owner?
Anyway, just contact them again and prove that you are the owner of the domain and that the text was online there first. As tufty said with archive.org for example. Also use a email with your domain to contact them. And put some unique file on the server (for example a .txt file with the same text that you just sent them) so that they can see that you have access to the server.
"Semper paratus!"
My BTC Address: 1F11EJvSAab5vMQgGWGQMASr9T7LCkZjvb