Welcome

I'm getting some new parts for my first fixed gear project. I'm desperately looking for smaller cranksets because i'm 5.6f and 170mm cranks don't work for me as my knees get super tired and also hurt sometimes...yes...life's hard... Does anyone of you guys know where to find 150mm cranksets? as 165 doens't really sound like a right size considering its only 5 mm less than 170.

Firstly HI!
Just wanted to say that 5mm actually make quite a bit of difference, but that's more in relation to pedal strike 'n toe overlap. If you're finding your riding position to be uncomfortable you're probably riding something that isn't suited to your size.There's more to consider than axle length when a comfortable riding position. Seat tube length, standover height, amount of exposed seatpost, have you considered these measurements yet?
I don't know if you can get 150mm SS cranks, sounds redonkulous.
Perhaps you require a can of HTFU.