Tips on not stuttering? Supplements to help calm me down?

Tips on not stuttering? Supplements to help calm me down? Hey guys. I’m 17 male and I stuttering a lot. It gets bad when I’m tense and I don’t stutter when I don’t think about what I’m going to say next but when I have time to think and get tense is when I stutter a lot. Any tips? Or any supplements that can help calm me down and not overthink what I’m going to say next?