Teen on birth control

i’m 13 and i just got on birth control.(pills) and i didn’t start right after my last period, i started in the middle of my cycle. so about a week and a half into it i got my period at the normal time i was supposed to (i figured it was because the hormones hadn’t had time to kick in and stop it yet) i thought it would be a light short period but so far it’s one day until i start the placebos and tomorrow will mark the 12th day i’ve been on my period. i’ve tried getting a hold of my doctor and she hasn’t answered, but i don’t know if it’s normal or not. is my period going to continue past the placebo week or will it stop? i know i messed up with when i was supposed to start taking it, but even then i don’t understand why i would still be on my period and if this is normal or not.