My 10 yr old was finally diagnosed with a mild “word competition” stutter last year after us noticing it since he was about 6. He repeats the last syllables of the last word and sometimes he entire word a number of times. After finally getting a diagnosis we did feel better, but since he doesn’t hear himself doing it we are holding off from speech therapy for now. I’m sorry you are already having to worry about this. My only real advice would be to take video often so you can document frequency, any changes and also start tracking how long it persists - and it will offer you some evidence if you feel like you are going crazy as we did. All the best to you!