Try writing out what you say during the presentation. Then practice presenting your speech. Practice in front of family or anyone you normally stutter with. Focus on slowing down your speech rate, to a crawl. Almost like your talking in slow motion. Take you're time pronouncing the sounds in each word in your presentation. Try varying your pitch and volume at appropriate moments. Like when emphasising a point. And include plenty of pauses. About 4-6 words for every pause. Make sure you use those pauses to ensure you're never out of breath. You shouldn't be though if you're properly reducing your speech rate. Practice your speech repeatedly. It's up to you how many times. I recommend at least practice for an accumulated time of 30 mins to 1 hour. You can divide up the time of the span of a few days. Maybe 15 mins 3 times a day.