Hi vintervargen,
Welcome to the sport!

The average 85 kilo rider will ride a 10m in Perth for most conditions. You add 1sqm for every 10 kg of bodyweight, (roughly) It's a formula I seem to have some success with.
With your body weight of ~110-115kg, that means you should be looking for something around the 12-13m range.
Something you need to consider is that some kites are much more powerful than others, for instance, the difference in power between say an Ozone Catalyst 12m and a Core GT 12m is quite substantial.
I'd be looking for a powerful 12m, it'll just be more fun. CHeck out the North Rebels, or Fuse, Core GT or GTS, also Airush Lithium/DNA.
We have most of these kites available, some in 2nd hand, some superceded and some new.
Hope this helps,
DM