The analogy that the medium described, about a more common route for people to follow (and she being prophesising that) makes me think that she might be picking what would be most common for anyone (almost statistically) and, if she told you that, then it would be more likely than if she went with more specificities that are not statistically probable (such as you becoming an astronaut and being the first human being to step on a planet on the Andromeda planetary system).

I don't know if that's what it was, but that's what I got from the analogy that you described. I don't necessarily believe in mediums and such, but I don't reject them as impossible either. I just think that it's unlikely given the explanations in the post, even though that makes me an utter sceptic without cure (and sometimes I'd love to be able to believe more of what people say, since life seems more beautiful when we can adore the divine and not feel repulsed by its imposed fictional authority).

Have you watched the Mentalist? I'm not saying your medium was like that, but I think that there's ways to read a person and come to think of a person's probable future from their current circumstances and their personality.