Hi penyt, I am also from Aus, Melbourne in fact. The thing a lot of people from OS seem to forget is that here we have shitty snowfall and shitty resorts (in comparison to them) Now my wife is 5'7 and about 60kgs (132lbs). She rides a DC biddy 143 and seems to love it, she is still a beginner but the board has been great for her and her progression. She doesn't go super fast yet and still is getting her turns dialled in and in this respect the board has been excellent for her.
Now if you were to be riding powder all day or bombing blues and blacks flat out i would say you would need to go longer but it may be that you can use this board until you progress past it. Where did you buy it from? if you are from melbourne i suggest going in and seeing ballistic to get some more advice, they are really good at pushing all brands and not favouring one so you will get an unbiased opinion.
my names's Petey and i have gigantic balls