I'm an SLP. Talk to the school SLP and guidance counselor about the possibility of having a 504 instead. 504s are for students who need accommodations for medical conditions (a diagnosed fluency disorder would be one) but do NOT need special instruction. IEPs are for students who need special instruction (like being pulled out of class to recieve speech therapy) in addition to accommodations. If you think you still need speech therapy through an IEP they can absolutely reevaluate you though. If they won't listen to you, have your parents request to have a meeting to review whether an eval is needed. If you're confident with your communication and don't feel you want to continue to work on strategies but just need this teacher to stop being an ableist butthead, 504 is what you want.