Flat Chested Issue

So I’m in marching band for the first time this year and my instrument is super heavy. I’m not weak I do powerlifting and stuff but the harness I have to wear really highlights the fact that I’m flat chested. There’s this one guy that always makes fun of me for having and ass but not having boobs. There’s also another guy who I really like but he’s gonna see that I have no boobs. I’ve gone along with the humor and amitted I’m flat chested, but I’m done doing that. What am I supposed to do?