This is just an artistic interpretation, not to forget Beleriand in relation to Eriador is about the same size,here it is oversized a lot, if you look into the Atlas of Middle Earth^^ see here i found a link for you, [link]
I actually did a Facebook post not long ago about how Galadriel is one of the most fascinateing characters in Tolkien's universe, because by the time you reach the 3rd age and the events of LOTR, she is the only character that existed way back in the time of the Two Trees and the first age. (well besides Gandalf when he was the spirit Olorin). but its really neat if you think about it...she is Ancient and has possibly seen and knows more than any other being in all of Middle Earth. so when you hear her speak at the beginning of Fellowship of the Ring it just feels all the more appropriate after considering all of that, ya'know?