Help with perfectionistic anxiety/hyper fixation on walks?

So I have anxiety and ADHD (and am a crazy perfectionist) and I recently got my first service dog prospect to be a medical alert dog. He came to me trained in the medical alert, but not much else (so leash walking is a work in progress). As I found with the fosters I had before him, I have a tendency on walks, if I don’t think my dog is paying attention or is pulling, to hyper fixate on what is not going well and spiral. I then basically perseverate the entire walk that I’m doing everything wrong, which stresses the dog out, causing them to paying less attention to me, causing me to get more stressed because I think I’m being mean and become even more anxious. It’s a super fun destructive spiral, which I’ve found almost impossible to just “snap myself out of”, even when I notice it. For those who self-trained a psychiatric service dogs, or anyone with just a similar experience, how do you manage this?

Like yesterday I had a perfect, calm walk and this morning I felt like screaming/ crying the whole time cuz I was messing up my dog with every horrible mean move I made.