I noticed with mine it’s basically all social anxiety, I’m so worried that I’ll stammer that I end up thinking about it and doing it, but when I’m by myself I’m basically fluent, I found being confident helps bro, and slowing down. It sounds like your family is negative about your speech, why is why your more worried about your stammer which won’t help whether as strangers don’t even know anything so it’s more relaxed. If there’s a girl that’s interested, I would just tell her about the speech impediment and if they truly like you it shouldn’t really change anything between you.