Assassin and crit%

I hear people talking about how easy it is to get a high crit chance as Assassin, meanwhile, my Cyclone says 17.5% crit. 30% from the ascendancy tree didn't even give me 2% more even though I was told that is base crit. What on earth am I doing wrong, I'm so confused.

This is basically my build (not including gear): https://pastebin.com/79dYmRxd

You need power charges and way to sustain them, and the next ascendancy point deadly infusion.

Ok, thanks..