I am confused about newborn sizing, and how much of it I need. I have been buying a lot of stuff from Baby Gap and they don't have a newborn size, they just start at 0-3 months (7-12lbs). I like this size, it makes me feel like she'll wear them from birth to 3 months.

But at Carter's they have newborn, which is like only up to 8lbs, and then they have 3 months. There is a HUGE variance between the two.

How much true "newborn" stuff do I need? And let's just say she's 8lbs or a little under (she's measured perfect to the day, never ahead, so I'm not expecting her to be a really large baby)
will the 0-3 months or Carter's 3 months really fit her?

Right now she has 4 or 5 sleep and plays in Newborn from Carters, and a couple of onesie/leggings outfits in Newborn. Everything else is 0-3 months from BG, but the onesies - especially the footed PJ ones - look HUGE!!!!

Any advice is appreciated!