RE: iSonic 133 or 122 ???
If an 8.5 is your biggest sail I would not go bigger than 122, maybe even 115.
I have the isonic 125 that works great with a 9.0m2 and 7.7m2.
I'm a bit heavier than you 92kg, so with the 125 I can comfortably sail back when the wind drops.
I would only get a 133 in combination witha 10m2.