That is so frustrating. I remember during a vacation right after my breakup that I spent practically the entire day immobile, letting thoughts swirl in my head - it was astounding how much was going on in there. I had never experienced that before.
What I can say is that with time, it will change. I didn't think it would, but it did, and I feel so much better.
One step at a time. At six weeks, it sounds like you are doing really well.
