gaining weight from bc

OK so I'm 17 and I start birth-control about 6 or 7 months ago over the time I've taken it I have gained around 10-15 pounds. my doctor told me it wouldn't make me gain weight. i'm debating going off of it to see if makes me loose weight. but do i tell my doctor i want to go off or do i just stop refilling my prescriptions? also do most girls get a worse period after going off? (mine was pretty normal before)