I knew I girl from China who stuttered. She is sucessfullty working as a teacher here in the US now. China does not have the support systems to deal with stuttering. In the United States we have better supports, therapists, and general understanding of stuttering. You don't have to be shameful about stuttering. You can accomplish all of your goals and stutter at the same time. No one will care that you stutter while taking your TOEFL test. Don't let fear hold you back - just continue to push forward and confidence will build over time.