Social anxiety and stutter, an insane endless loop for me.

Social anxiety and stutter, an insane endless loop for me. My stutter is probably mild on average... I can talk 100% perfectly when I'm alone, but it gets exponentially worse if I am just a TINY bit anxious or ashamed of something. It's literally like an anxiety meter. If I am very anxious I block even with my name. I have severe social anxiety as well, so the more I feel anxious the more I stutter. The more I stutter and the more anxious I get. A vicious cycle. Spoken uni exams? I literally got lower marks a few times because the blocking was so bad. Having to start a phonecall with someone I don't know very well? The worst. I had to call a restaurant today. It took two days of dreading anxiety and more than half an hour of me waiting to calm down with the phone in my hands staring at it before calling. It didn't even work because I had a block that lasted 4-5 seconds and the other person completed the sentence. Can you imagine having celiac disease and blocking every time you have to say gluten free? Another example? My mother is friends with the vet where I bring my cat. A few years ago you could go without an appointment, but then it became mandatory to call and schedule it in advance. I did it and blocked so hard that it took a LONG time to even say my name. Now I always ask my mother to call her for the appointments..... Long story short? It's affecting my life too much but I don't know how to get better.