Don't worry you'll be fine! .......That being said I failed twice, once for not knowing the speed limit when randomly asked (inner city so had to be 50) and once for the instructor having to intervene haha.
I've always been such a careful driver as well, nerves sure can get the best of you sometimes.
But that being said none of the questions were technical, you just do the theory, get in the car (drive, parallel park, 3 point turn etc...), and then do the hazards test which is very, very easy so don't worry!
Note: I took my WA driving test in 2009, so some aspects may have changed since then.