Vowels are HARD!!! What works for me is to really stretch the first sound of the vowel like a....bout. Does it work always? No but at least I try! I have started to do “ums” last year and someone I work with said that it’s an anticipatory thing we do! We anticipate a stutter and put the um or uh so we don’t lose our flow. Idk about you but it annoys me so much. Taking out the ums helps see what stuttering actually is helps to try and work on it with strategies. It’s not easy to hear what actually does come out when you take those ums out but you can manage the stutter better by taking out the ums, or trying to self monitor. Idk if that helps but I hope it does!