Puberty questionnn!!?

ok im 13 and im still going thro puberty most girls are already done and on there periods and i tell most of my friends that i already gotten mine to feel not left out. so i lyed and im ashamed but really i have like no my mom has huuuggee ones like double d's im maybe 36 A; heck prolly 34 A when do i get my period i already show the signs of puberty and i know for shure im going thro it but im going to 8th grade and i dont wanna be flat chested for banquet i mean i wont be able to fight in any dress cuz im so flat.... PLEASE HELP!!