Man, im 23 and have the exact same problem! Vowels, especially at the beginning of a sentence, are hard for me to get through. The worst thing is my name is Ethan, I haven't been able to say my name,fluently, in years! I go by my middle name now. I also stutter worse when im asked a question or when someone is waiting on my response so I know how you feel. Don't worry, as you get older you'll be less embarrassed by this. I own a home renovation company, and when I start to stutter with my clients, I simply tell them I have a stutter and the mood brightens up lol. I wonder why vowels are hard to say for us hahaha sometimes it's a bitch😂. Best of luck buddy and don't let the stutter put you out 💪