I define a close pass as one that causes my bike to wobble, thereby putting me in danger of hitting the deck. This could be because I've instinctively flinched or swerved, or something to do with the laws of physics and air flow. Anything else I don't notice. That might be right or wrong, I don't know. Nor do I care. It works for me!
I'm also a lot more confident on the road now and ride in secondary, happily moving into primary to pre-emptively prevent a silly overtake if it's a blind corner and so on, but also briefly moving to the side to allow cars to pass if it's suitable (not if the road's potholed / littered etc) and trying to be as considerate to other road users as I'd like them to be to me. It's a style that works for me in my particular neck of the woods, including the main A roads from Taunton to Minehead, Bridgwater, Wellington and beyond.