I think you are looking at it wrong. The foundation of your stuttering is likely highly connected to your name. Because our name is like the title of our ego, so our brain and body is most effected by our ego. If your name started with a vowel, you might struggle with vowels more than the letter D. Though I do understand that some consonants have a more powerful sound than others, making them more difficult to an extent. Though ultimately I think we need to work on our relationship to ourself and others so our name is more comfortable to us.