Seems like your stutter is tied to your anxiety like mine. The best thing for me was just exposure therapy and anxiety management. I just don't avoid any of those situations that I find hard because you avoid them they become worse. When I notice my stutter is worse then usual overall I'll take 10 minutes a day to just sit quietly with my eyes closed, breath and focus on relaxing. It's not an immediate fix but it decreases my anxiety over all. It's basically meditating but without the hippy-ness. I mental trick I've learnt for the moment when you feel really tense and anxious and know you are going stutter is to look past the moment. If you just think in 5 minutes the waiter will have been and gone and it won't have really mattered if I stuttered or not because my order will be done. This perspective change helped me alot when I was younger. If I was having a really bad anxious time. I'd just think to myself "is this situation bad enough that i won't be just sitting at home watching TV later and what's happening now won't really matter much?" If it won't really matter after the moments passed you can relax a little more during the moment.