Not much advice to offer, but I just wanted to let you know that your post and comments here could've been written by me. The covert block stuttering, 10x worse in "official situations", fluency when talking to just one person or in speech therapy. Just know you're not alone. I'm trying to tell people I stutter right away so that when I do start blocking I can brush it off with humor like "lmao there's my stutter again". I don't want to have to rely on it all the time, but when people know about the issue it just makes situations so much easier. I remember one tactic I learned in speech therapy was to "ease" into the word if it begins with a vowel to help with blocks. Like for apple you would say aaahhhhpple. Softer sounds can be easier. And if it begins with a consonant then "tap" the beginning of the word and say it really lightly. It can be weird in practice but it does help eliminate explosions and helps you maintain a better flow. It might be worth it to try!! Thank you for posting this!!