Have you tried speech therapy? It has helped me alot. I signed up with the office of disability at university for one semester. Worst decision of my life. This allowed me to present a project to my professor one on one as opposed to presenting to the entire class. Everyone knew I didn't present my project and gave me a weird look, and I still ended up stuttering a lot during the presentation. Had I done it to the entire class I would have had the accomplishment of getting over my "fear" and presenting it the same way as everyone else. I have never avoided class presentations since.