people can't hear me and i'm always asked to repeat.

people can't hear me and i'm always asked to repeat. I hate my stutter, today when I was in class the teacher asked me to answer the question, so of course I said yes and proceeded to answer. When I answered she asked me to repeat; after I did, she asked me to repeat, and again and again, and when she finally heard me I stuttered ALOT. How do I fix this problem? My voice is low, but for me it's high and people don't hear me.