No, The Sun and Moon are Squared, so you are a tad stubborn, but that isn't it. It's Mercury which rules the mind, and since your Sun is in Taurus, it could be there, or in Aries or Gemini. It rarely goes more than one sign before or after the Sun. I'm going to guess it's in Gemini, because a Gemini Mercury will keep you up nights because you can't shut off your mind, or because you think about too many things at once.
Otherwise, if I have to choose from the three positions you gave me, I would blame it partly on the Aquarius Moon. Those air signs always keep you going. The Moon rules your emotions, and in Aquarius, you have very changeable ones. You could be thinking about past feelings too much instead of moving on.