Why am i so flat chested??

Im 14 years old and i still practically wear a training bra! sometimes i use sports bras but nothing! my chest is flat and my mom and grandmother make fun of me about it. which is stupid because they both bought themselves boobs! all the other girls my age are already delveloped and i just feel left out i guess. plus my quince is next year and i want to have boobs to fill in my dress. is this normal? ps. dont say i should be happy with my body.