you should put an h before those vowels. for example, “open” would sound like “hopen” and after would sound like “hafter”. It sounds weird and can be pretty difficult to do in a serious conversation where you experience a block but if you convince yourself to go through with it instead of saying “o-o-open” or “a-a-after”, it’s pretty rewarding and can breed confidence in future speaking situations. It’s comforting knowing that you CAN say them (albeit a little different than normal) and nobody would really think twice. Then sooner or later that silent h should fade and speaking feels like simply breathing, rather than forcing hard glottal onset’s that sound like your throat is clogged(basically what stuttering is). Don’t be afraid. I’m working on the same thing myself. To answer your second question, i think it’s because the more pressure you put on yourself to be fluent, the worse stuttering gets. I feel confident in guessing that you don’t stutter alone or when talking in the mirror. That’s how it feels when other people talk. It feels like how you feel talking to yourself. I think the reason for this is that stutterers see fluent speech as success, and disfluent speech as failure. We care an awful lot about how other people view us compared to non-stutterers, Probably because we were raised trying to make everyone around us happy by speaking perfectly. This insistence on speaking perfectly is what causes those brick wall blocks ALL of us get. We don’t want to stutter, but our voice won’t allow us to speak at our desired speed(stutterers have this unreasonable urge to talk 200 words a second). To summarize, you may feel better just speaking as if you didn’t care if you stuttered, but use the silent h when you are in certain situations. You’ll know the situations when you’re in them. Hope this helped!