No stress! It is a bit of a different thought process. The coordinate system makes a lot more sense both mathematically and when you do 3d manipulations/work in 3d environments. Coming from pixel space and 0 - 1 / Width - Height space to that can be a bit of a shift though! I have ripped out a fair few hairs when transitioning to this kind of workflow myself. As it is standard for most applications in 3d space I guess it's just a matter of getting to grips with it.