Stuttering isn’t usually at random intervals. I’ve had words that were never a much of a problem rather suddenly become a word I stutter on every time. Same thing happened with certain letters and sounds. The severity will usually change over time though, sometimes I might even stop stuttering on the word or letter completely. It does seem like your stutter is rather mild considering it’s only after high stress situations and only on specific words. So just think of a few synonyms for the problem words to use instead then practice saying the difficult words in private over and over again at different speeds and volumes, and pay attention to all the little things that you’re doing when you say the words, until you’re confident enough that you can say it around other people.