I do this to my bf too. I don’t mean to. He does exactly what you do and also says I’m not right and I need to let him finish. I then try to patiently wait for him to start over and get the whole thing, only to find out it was exactly what I thought he was saying to begin with. lol I know it’s frustrating to talk to me. I’ve been told it all my life. I try hard not to do it, it happens involuntarily most of the time.