My mother and most of my relatives are having very developed chest but I'm very flat chested

Hi im gonna b 15 in a few months, i got my period at nine my lower body isn’t flat but that’s mostly genetics my momma curvy as hell. Her chest is very developed and so is mostly the rest of my relatives. Its just my chest is sooo flat. I eat all that protein and potassium n the exercises but my chest is flatter than a 5th graders