If your looking to build a perfect model it will never happen.
If you loose your temper real easy you need to work on that all the way around in your life.
It realy is bad for your health,and can get you in trouble.
As for progress I scratch build a lot and at the end of the day there dos'nt seem to be a lot done sometime's.
But then again your one step closer to the finished build.
I kept a record of a build one time it involved a lot of scratch building.
Talk about a progress problem.
As for the anger issue step away calm down and get back to it.
230 piece's to make the part's for the car.
260 Hrs to build the car and that's not counting the time for research and keeping record's.
This is a hobby to help you relax not beat yourself up.
Take a kit paint it,build it,regardless of somthing not being right and don't worry about it.
And most important build for yourself not anyone else.