Why does my best work always carry someone else's name?

You do excellent work. Someone else signs it, presents it, and gets promoted because of it. You tell yourself it doesn't matter. It does, or you wouldn't be reading this. You did not stumble into this arrangement. You built it, one handed-over report at a time, one meeting you skipped because someone else would 'present better.' It continues because you keep allowing it to continue. There are only two honest moves from here. Ask for credit, specifically, before the next project starts. Or begin building toward work where your name attaches to what you make. Everything else is just patience dressed up as a plan.