windreams said..
There’s guys out there with more experience than me but here’s my recommendations for what their worth.
I’m 72kg and my most used kites are 9 and 12 hybrid types, so at 65kg I think you would use a 10 more often a 12 especially around SEQ.
Without knowing exactly what knots you were kiting in on your Thailand trip I can only guess they were around 11 – 15 as I have been there twice and both times that was about the average, hence why they had you on a 12 -15 also the wind feels less dense over there.
Do a bit of research on a few preferences then drop into a couple of your local kite shops and ask them what they reckon…
Just realised I made a typo, it should be; I’m 72kg and my most used kites are 9 and 11 hybrid types,