The work place is tough because we don't want bosses and co-workers to know about our PTSD and have judgements. I am a high school science teacher in an inner city school. What I did was to make a list of things that I found hard to do at work. Then I tried to plan strategies to overcome or compensate for them.
You said that part of your difficulty is self-confidence and interacting with people.
The checking in with your supervisor for positive feedback will improve your confidence. Also learn to evaluate yourself fairly and accept when you really did a good job on the system you manage. You need to feel you are accomplishing things each day - make a list of things you did at the end of each day as a work journal - that will build up your self-confidence and be something to show your supervisor at your reviews. Sometimes if an employee has a lot to offer with minimal flaws the flaws can be ignored or minimized by supervisor actions.
As for interacting with people, that's a tough one if your anger is just under your skin. You need to vent some of that in a positive way, ex: exercise, writing in a journal, dealing with the source of the anger and focusing its energy on changing things or accepting them (it is what it is). Learn some anger management tools that will work for YOU. On my bad days, (this will sound stupid but it works for me) I carry a coin or marble in my pocket. When I'm getting really tense or on edge ready to let go I squeeze the marble really hard to focus the energy. Whatever token works for you it should be meaningful- dogtags? I've also learned just a short walk through the halls focusing on my breathing can break it before I lose it. The point is figure out what you can do to break the cycle and allow you the time to regain your composure until you can react calmly with purpose. This is very hard to do - but practice makes perfect.
The first step is done - you recognize the problems and why!
However, some of what you describe could also only be your perception of a problem that doesn't exist. I've done that before too.
Stick with it! We are here for you.