When you are invited to speak or asked to give a presentation, the reality is you will never be given all the time you’d really like to have. I believe a big contributor to the high level of anxiety folks feel about speaking is a nagging fear that we will leave out critical details and not cover everything we’re expected to discuss in the prescribed time frame.
Skilled speakers pack every minute with relevant, valuable content. They are not afraid to cut out material, even if they think it’s important and may be a bit sad doing it. They also keep their comments within the time for their 
program and can shorten on demand if the agenda needs to change. These skills are acquired with practice, not overnight!
A trap I often see is speakers with too many slides. It’s helpful to understand that not every point needs to be talked about with a visual. In fact, some nationally-recognized speakers are leading a revolt against what they call PowerPoint abuse. Instead, speakers are showing pertinent videos they’ve either created themselves or excerpted with permission (and sometimes without) from the source.
Other speakers are opting to return to the traditional speaking style of yesterday, sans electronic devices of any kind. To go without visuals demands that your presentation or speech be top-notch, compelling and you are fully comfortable and familiar with your material.
I remember upsetting a conference director who had invited me to speak because my flash drive had 100 images and my talk was only supposed to be 15 minutes. She was rightly concerned that I’d run over and cause everyone else to run late. I assured her that I was only using 20 slides. Moral of the story: when you’re invited to speak, honor your time commitment and only have the images you’re actually using in the file for your presentation.