The best way I've found to help myself be more fluent is to take a deep breath, but push out my gut as I inhale & try to move my way up to my chest if that makes any sense. You can probably get a better description by watching a video or something about diaphragmatic breathing, since I'm pretty sure that's close to what I'm doing. I was taught how to yell using my diaphragm when I was a drill sergeant & I actually noticed that I NEVER stuttered when talking or yelling like that, so I tried adapting it to how I breathe & found a lot of success with it. It's hard to tell when you're doing it right at first, but you'll notice it when you do & it becomes more natural over time. It may help you or it may not, but it’s worth a shot either way.