Something to try is not using filler words. I know it's not all that easy when you're just trying to be fluent, but you could say "just a moment" and take a second or two until you feel like you can get the word out. Or if you're in the right context, roll with it. But if it's something that bothers you, you can find a work around. Initially it will probably be frustrating because it's sort of a shortcut to fluency. But the more space you give yourself to stutter (and breathe, don't forget) , the less frustrating it might become. I'd like to hear what other people do in this situation too.