I have an idea that might help you. Instead of wearing headphones, how about earplugs? They are much more discreet. You might have already tried this but if not hopefully earplugs will help you. I’m in school, and earplugs often help during tests.
In terms of eating, if you are eating with someone you are comfortable with, try putting on background music. It may not completely erase the sounds, but it will help.
My triggers are all related to the nose, sniffing, snorting, sneezing, etc. As mentioned before I use earplugs, and I hope that they can help you.
Best of luck.