I’m a late onset stutterer as well. I’m a 33 yo male and started when I was 28! Mine started at the tail end of a bad battle with alcoholism. My stories kinda similar to yours. It started out very mild, and then one day I could barely carry a conversation without fumbling at least one word a sentence. No history of stuttering as a child I should add. Brain scans haven’t shown anything. Speech therapy at various points has helped, but not drastically. I should also add I’m on the autism spectrum (diagnosed at 32). I imagine our brains being wired differently definitely plays into it. Not to mention the horrendous amounts of stress we can experience. I hope late onset stuttering is better analyzed moving forward. I’m a bartender so I deal with uncomfortable interactions almost everyday. It definitely gets exhausting. Hope you find answers!