As a person who has never been diagnosed with PTSD, I’m not sure if my advice will be helpful to you at all, but I’ll put in my two cents anyway. I used to be possessed with crippling social anxiety disorder. I was more or less silent around people I didn’t know very well from the time I was maybe 12 years old until around 18. I was terrified of saying stupid things or being laughed at or making people dislike me, so terrified that I couldn’t even speak. Interestingly, this had the effect of causing the very thing I was afraid of since people who won’t talk seem rather suspicious, strange, and difficult to like. But that’s off topic.
Before I could get confident in speaking Japanese, I of course had to become confident in actually speaking English. So let me introduce you to the process.
First, I took a job as a waiter in a restaurant. It was terrifying! But gradually I got used to communicating with strangers. It helped that I was getting paid to do it.
Next, I moved to a new city. There was NOBODY there I knew at all, so I HAD to communicate with people I didn’t know. It wasn’t easy and I was depressed for a long time, but gradually I made friends and I got a little better at talking. Mind you, during that period my lack of social skills did earn me a lot of dislike from some people, which was exactly what I was afraid of, but life went on and gradually I learned to see those people’s negative attitude towards me as something that was as much wrong with them as it revealed something wrong with me. After that, it became easier to deal with.
Finally, I moved to Asia and took a job as a teacher. Now I was a professional talker and communicator for a living. I felt like I was dying every time I stepped into the classroom. But after a few months, it started to feel natural. During that time I also lived with a host family and they couldn’t speak any English. I had to communicate (in Korean it so happened, but same idea). Basically, I was in situations where communication was essential to my life; I had to step up, so I did.
At this point in my life, I’ve given several public lectures at universities and I’m still a teacher. I still get a little nervous sometimes, actually really nervous, especially when I go to job interviews that will be conducted in Japanese. But I came a long way.
Long story short, you have to put yourself in situations where you have no choice but to do it. And you have to get yourself in the mindset where you realize that “failure” do achieve what you want is just a lesson teaching you where you need to improve. It’s not your deficiency, it’s your data on how to improve.
