i got a starlet GT and i recenlty changed the oil about 2 or 3 weekends ago. Oil is definately not leaking from anywhere yet when i went and checked it today its gone form full to somewhere between full and half

I'm getting quite a bit of oil coming out of my BOV also, and when i leave the car to idle for say 2 minutes or so, i start getting billows of blueish/whiteish smoke out the back but when hte car is drving around its sweet no smoke whatsoever. its holding boost etc perfectly as well.
what do u reckon guys?