I feel you. When I'm stuck on an St/Str word I stop and use the word with the previous one.. So if I'm stuck on "Street" I would stop and say "the-street" in one (exhaled) breath. Over the last few years whenever I stutter, I explicitly tell people that I have a stuttering condition, they just say "oh that's OK".. Sometimes that helps me a lot with speaking fluidly-ish. I realized I stutter a lot more when I try to hide it from people.