(Unsure if this is a bot) I hope those supplements work for you. You should limit it to just one supplement at a time during your testing phase. Perhaps try 5-htp first for a few weeks because there's arguably more well-established research on it. Those supplements you listed also affect neurotransmitters like serotonin and dopamine in different ways so it's safer NOT to amplify their effects that quickly. Also keep in mind that your stuttering might not be due to serotonin/dopamine. There are other causes as well. Take a look at the research paper I included in my first comment in this post.