A metre isn't enough

ev_, it sounds as if you're already doing a lot of things right. However, don't adopt inflexible rules about your own positioning. You should cycle relative to traffic, not to measurements. Yes, keep well away from the door zone. This is called 'taking the primary position' and is sometimes in the centre of a lane (if it's narrow) and sometimes just to the right to where the left tyre tracks of most cars would be. However, the distance you keep is not intended to keep you 100% safe--don't relinquish your alertness. It is meant to give you extra room if you need to take evasive action. There is no need to take the primary position at all times. You will develop good judgement of when to take it and when not.

this is what I wanted to say, but could not articulate it as well as Oliver.