Im from nz too, buy from sheplers, great! I'm 5'4 67kg, size 10 to 12 jeans nz and i buy 7/32 which comes actually 7-8 32 is the length of th leg inseam (we can't buy different length leg in NZ, sooo good).
My next pair im going to order is a size 5 though. They stretch quite a bit like all jeans with stretch. I have the Ultimates and the Booty Ups, i find they Ultimates slightly larger fitting.
Take care ordering ti NZ you will get stung at customs with duty and GST. Keep the order under $200 approx, the GST amount has to be under $60 not to incur charges. I just ordered $400 worth NZD and had to pay another $153 to get it released.
Hope this helps