Have you tried an FM system at work? I've been out of the workplace since retirement 10 years ago, but used an FM system often when I was working. The technology requires telecoils in your hearing aids to use appropriately for a severe hearing loss. It was a lifesaver for me. I also had to adjust switching from analog to digital. It took some time, but it was worth working on. While external mikes work best when they are close to the speaker, there are microphone devices that can be placed on the center of the table. You are using technology that is rather old, including your iphone, but I know a neckloop can work very well with the iPhone 5. Have you ever tried using a neckloop with your phone? You have to have telecoils to do that too, but thinking that older analog hearing aids might have that feature.