I'm not sure why it matters whether I am riding "just to the right of the centre line" or fully in the middle of my lane. I'm also not sure whether you mean you're being crowded by other bikes or by bigger vehicles.
Either way, I would practise (or is that "practice"? Damn you, childhood reading Agatha Christie and Ruth Rendell! Must remember, it's not a car park, it's a garage!) the same courtesy I would in a car. That is:
If I am going straight, and someone behind me wants to turn right at the corner, if I can safely move up and far enough over to let them pass, I would do it, just as I would hope they would do it for me.
If I am going straight and so are they, there is not likely enough room for a car to sit next to me in my lane, but another bike is welcome.
If I need to turn left, I am probably gonna position myself in my lane to safely make my turn and protect my space. In my mind, that is fairly center, I don't want cars scraping past me on my right, I'd rather they HAVE to stop until I turn. (But I can see the arguement for positioning to the left and hoping someone going straight and doesn't see you won't hit you...but I think my reasoning is better.)
Not too long ago on my way to work, a guy on a HD stopped at the in left position, and gave me room to pull up on his right. We nodded real friendly like. Light changed, and I left him in my rear view mirror. I sort of felt bad, but nobody forced him to buy a bike with lousy acceleration!