I feel you. I have been stuttering since I can remember. One day I said fuck it, and started to improve myself. It took a lot of time(2 years) and a lot of disciplined effort. I can explain all about it via DM, if you are interested. You need a booster to your confidence. For me that was weightlifting, for you it may be something different. The important thing is to be something that has a clear path of progression with visible results of your hard work. I wish you luck on this journey, you can do it!