What does "I would have thought" mean here?
I would have thought there was nothing in that to disturb me. But I felt uneasy, and I wasn't sure why at first.

* I don't understand what "I would have thought" mean. Is it different from "I thought" or "I had thought"?

Question

What does "I would have thought" mean here?
I would have thought there was nothing in that to disturb me. But I felt uneasy, and I wasn't sure why at first.

* I don't understand what "I would have thought" mean. Is it different from "I thought" or "I had thought"?

Answer

This is a very British way of saying, "I would have imagined."  It means you are trying to think how you would have thought/felt/answered, etc., before such an event took place.  For example:

"I would have thought I'd be very happy when he asked me to marry him, but when he actually did it I felt uncertain."