Hoenstly, it sounds to me as though it is going to take you some years yet to really find the right path for you. I also started out in biochemistry, did part of a PhD, then spent many years working overseas, and now another PhD. These are indeed difficult interests to rationalise. You are being very sensible in your choice of topic. I also started out in cancer reaerch - but unlike you I hated lab work so I expcet you could do this perfectly well if you choose. But actually, as I've got older, I've got less sensible as I've realise my 'real interests' are not going away. Maybe you will settle happily into a long career in biochemical research - or maybe you will reach a point where you need to take more of a leap of faith and not worry about your family's opinion (believe me - that gets a lot easier with age).
But you need to do something right now. If you can't take time out to travel (language or science teaching is very portable and will take you anywhere - your family might find that more respectable too) then the PhD in Australia seems like a good compromise for now.