Find a good slp who specializes in stuttering. As an SLP myself (who also stutters) I can tell you that we are not alike in this speciality. It’s funny you say you practices speech’s in the car cause I do that as well. I’ll practice them over and over again until my meetings where I can just run on auto pilot fluently (almost an out of body experience) and not think about my speech. If I speak from the hip, I often all over the place.