Incidentally, my W also would just say "nothing" when I ask her what's wrong or just "fine" when I asked her how her day was.
So what I learned was to ask questions that required more of an answer. For example, rather than asking "how was your day?" which would just get me a "fine" response; I would ask "so what was something interesting you did at work today?"
Just something like that. After awhile (and it takes awhile) my W started opening up. Now we are actually talking better than we did before.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.