Stuttering is not only repetition, blocking is also part of it. I'm the same as you, as in I block mostly in anxious situations, like presentations and interviews. What I noticed is that, in my case, mental health and fatigue is what contributes the most for my stuttering. Lately I haven't stuttered much and have even gone through presentations and interviews without issues. I know that it's not recommended in general, but one thing that I do is swapping word/sentences to avoid blocks. For me stuttering has a sort of snowball effect, where if I start blocking, I lose control and it's hard to stop and get back on track. But if I dodge words and keep the flow, I can keep going without issues. Note: again, I know that swapping is not recommended, but it's what works for me.