Sorceries obtained in the DLC do not count.
You basically cannot mess this up on a single new game cycle as long as you make sure to free Big Hat Logan in Sen's Fortress and the Duke's Archives BEFORE KILLING SEATHE. Then you can meet him in the library area in the archives and buy the now available Crystal magic spells in addition to the rest of his spells. You will need a minimum of 15 Intelligence before you may buy spells from him. Then simply kill Seathe, and kill the now insane Logan where you first fought Seathe and died for a final exclusive sorcery. You can hunt the rest down at your leisure without anything being missable unless you do something really silly like killing Griggs, Ingward, or Dusk.