I'd say Iselin like "ice-lynn". So Iz or
Izzy wouldn't happen. Ice or Icy would though!
...ok I looked it up and I see that I'm saying it super wrong. Iseline would be the spelling that I'd pick for clearer hint on pronunciation. Also I feel like Iseline looks less like a modern name (which I originally thought Iselin was) and more Medieval Norwegian, which is bad ass.
What about
Lina for a nickname? Still not short enough for Australians?
Iselin Årolilja
Iselin Astri
Iselin
KatharinaIselin
KajaIselin Elida
Iselin
GenevieveIselin
KristianaIselin
MarianneIselin
AmityIselin
OdetteIselin Oliana
Iselin
HannaIselin
Silvia