WOW… Your speaking my language. This has been an ongoing problem for me too. I worked for a boss who said I was verbose and acted irritated whenever I tried to share. That led me down a slippy slope of self actualization and making it worse. I still struggle, but I do what you outlined above. I spend more time editing my message and spend more time using PowerPoint and other Office products to create my outline and speaking points. I then stick to it as much as possible.
I also type my thoughts on a Word Document and then start edit it down. I find that the new Word helps you by identifying sentences that are using too many words and offers you a suggested alternative with less words.
When speaking, I try to speak less and share only about 3 points at a time. I then stop, ask questions and get the other person talking. That allows me to be more responsive and only share what is needed.
Hope this helps.