I always wear a helmet. I took English lessons, but I have a western horse now and ride her western. Mainly trails and stuff. I really trust her and she's very calm but things can happen. Helmets save lives!! I don't think my mare would ever buck me or rear, but what if we were galloping and she stumbled. I could be thrown and crack my skull. No way - I stay on the safe side.
I think it is a personal decision, but for you - obviously being younger, you have to listen to what your mom says. Look into the helmets that are designed to look like Westen hats. They have some neat ones out there. Maybe you could get one of those and have the "Western" look but still keep yourself safe. And you should never feel ashamed to be safe - it really is important!
Here is one link - I'm sure if you google it you can find lots of others! Tack Wholesale.com : Quality Horse Tack & Horse Supplies : Troxel Western Hat Helmet [04-100]