Irina, Do you pronounce her name quickly that it sounds more like Olga or you speak it the usual as in Oluga?
I pronounce it always as Olga because that's how her name is spelled.

By the way, Tatiana's name is an ancient Greek surname. So, it had been used as a surname before it turned to a nice girl's name. History's just so wonderful.
But it's really a nice surname. If we use it nowadays, everyone would mistook it as your own name, right?