Interestingly, your situation is very similar to mine (we are also same age lol). I have always had a mild stutter that I could perfectly conceal. I went through school and university without much speech anxiety (there were a few difficult words but I just ignored them). I was also very good at giving presentations. However, things started to go downhill when I started working. I suddenly felt the need to speak fluently and as a consequence I started overthinking words (and yes especially words that I needed for my job). As you said, I always felt that I am hiding a part of myself and it started to bother me more. In my opinion, it's all in the way I speak to myself and the wrong conditioning of my mind. There are plenty of words that I stutter on now, but that I could say fluently 5 years ago. This just shows that it's a psychological problem. As soon as you start overthinking the words it ruins the natural speech flow. I am currently working with Lee Lovett's techniques. I just like his approach that stuttering can be beaten and I am 100% convinced it's possible. He also puts a lot of emphasis on mind training.