Question about the pill

Ok so, if you start your first pill on a Sunday, you'll end on a Saturday. So that means after your 7 day break you'll take your next pill on a Saturday, and end on a Friday. I over thought about this way too much and I think I'm making an obvious mistake, because every pack you'll start a day earlier. Is this right? Because I thought you'd start your pills on the same day every month. Sorry if this is confusing to read I feel like I'm trying to tell you a riddle. Someone please explain!!