I realize that this seems like a ridiculous question, because Brienne's father is Lord Selwyn Tarth, and as his daughter she will be known as Brienne Tarth.
But in every single reference I have found to her she is known as Brienne of Tarth. Even searching on the wiki for Brienne Tarth redirected me to Brienne of Tarth.
This makes no sense. I know that the island that she was born on is called Tarth, which I'm assuming is where her family name comes from, so this title makes sense (like Sansa of Winterfell for example). But why is the of always included?
She is the heir to Evenfall Hall, so she does by all accounts hold the name (she isn't a bastard), so why is she never referred to as Brienne Tarth? Is this even her name?