Your cards are wonderful, and I would have loved to receive them from a student. I am so sorry that you did not receive written thanks. I've taught for twenty-five years and make it a point to write a note for each gift. I've observed that my co-workers are faithful to do this, as well. I do remember finding thank-you notes in the bottom of my son's backpack on a number of occasions, so I always hope that the notes make it home.
Many times I give students notes to express appreciation and the student will,then, thank me for the card.
Although I make cards, I've never taken the time to make Christmas cards. In addition to mailing cards, I always give one to each of my students. There are always left-overs. I use those to write thank-you notes for Christmas gifts from students.