Stick your index fingers in your ears. If you can't do that because of finger nails, pushing the Tragus with your index fingers should be fine. I also recommend getting a good set of earplugs that are custom molded to your ears and try wearing them when out.
Get used to wearing them when you expect you might be exposed to overly loud sounds. Mine are "musicians earplugs" and have a flat frequency response so things aren't so muffled. They are pricy, but you're worth it. I have a pair I keep in a pill bottle in my pocket every time I leave the house. I do not depend on these for things like concerts but just for extra protection.
I no longer go to concerts, sadly , but T and H are life changers and we have to adapt. You may also wish to look into getting ear muffs to keep nearby or in your purse like Peltor or similar. Some muffs look like headphones so no one will think you are weird wearing them in public.