Trying again?

When is it ok to try again for another baby after a miscarriage, still birth or ectopic pregnancy? I ask this because I have had so many people give me different answers and I'm interested in seeing other people's views...most common answer is "when you're ready" but how do you know when you are ready? When does it become a desire for a whole new life rather than the wish that you could somehow replace or recreate the life that was lost?

I would like to try angain for another child but I am frightened of everything going wrong again - does this mean I am not ready or just understandably anxious about what could happen in the future? The desire to have another child is there but the fear of losing that child is also there - does that constitute an unready state?

What do you think?