birth control

so i've been taking birth control for almost a year now but i've noticed that for a while i'll bleed but it'll be more for than how long my period usually was and there aren't any cramps or anything and it's not a ton of blood , it's almost like spotting but it's been more than a week already so i'm not sure if that's normal or not , i usually get my period once i have to get my depo shot again which is like a week before my due date for my shot