It is very normal to feel horrid after an exam, regardless of how well you went, the atmosphere, environment of exams just breeds intense anxiety - so don't worry, your feelings are very justified! You might just surprise yourself when you get your results, so try not to be so freaked out. The psych exam this year WAS hard, as long as you knew your content, and prepared well, I think you'll be fine.
As far as future exams, I'm assuming you're a year 11 as this is your first exam? So next year you'll have the rest of your exams? To reduce anxiety as much as possible:
-Do as MANY practice exams in the SAME ROOM (if possible) as your exam. Eventually you'll come to understand that all exams are the same, and there is no reason to be anxious because you know your stuff!
-Be confident! I can assure you that a major part of exams is just having the confidence to keep up motivation and resist burning out. Just keep telling yourself "I can do this. I know my stuff".
-It might also be worth looking into "rest breaks". Due to my anxiety, I'm eligible for "rest breaks" throughout my exam where I get 30 minutes of time to just breathe and relax. I'm not allowed to write or read the paper during the breaks, but I can just, collect myself, plan my answers, and think about what to write. They are very useful to calm yourself down. If you think you have an anxiety or mental disorder of some kind (or can convince your vce coordinator you do lol), you may be eligible for these breaks in
your exams next year. There is a WHOLE range of reasons why people can get these rest breaks (death in the family, ADHD, etc), so perhaps it may be worth researching if you are eligible?
Best of luck with the rest of your exams! Remember that you are the only thing stopping you from achieving. Be confident, determined, persistent, and you'll have no reason to be anything but successful x