I can remember a lot of things I did screwed up
, but I wasn't overwhelmed by the rules. The first thing that popped into my mind was to wonder if the OP ever played basketball. Maybe being from Indiana and loving this game all my life was an advantage for me.
Rut just gave you some excellent advice get the SI book and keep it simple. You will probably find yourself in a room of officials arguing the most complicated rule in the book at some point. Remember this, those officials probably couldn't referee their way out of a paper bag and those complicated rules are great to know, but will probably never happen in your career - UNLESS you become an official who looks for them to happen.
If you are anal (like me) you can lessen this feeling you describe by taking care of several things that you can take care of before you ever step onto the court:
1. Know the rules and their application
2. Make sure your uniform is tailored, shoes shined (somewhat at least)
3. You are in good shape.
4. Your mechanics are perfect when practiced in front of the mirror. Your mechanics will slip a little in action so settle for nothing less than perfection while practicing. Use mechanics that fit you while still following the rule book. Steal mechanics from officials you like.
5. Become comfortable with doing things like blowing a whistle and raising your hand. It isn't really something natural.
6. Get in front of a mirror on a treadmill, if possible, and look at how you run. Remember you aren't playing basketball so don't really run like a player.
Sorry for going on and possibly getting off the subject.