Im going to carters for my reborn baby doll on my birthday and i wanted to know if the sizes there will?

fit her! ive bought clothing for her before , and its really hard to tell what size she is i brought her 3 preemie size outfits at walmart ,and they where made by carters and they fit her perfectly but they where tight and the chest part showed a little part of her cloth body and those where the baby sleepers but then i brought her some clothing from faded glory and it was size newborn and it was really baggy but then i brought her a onesie from gerber and it was 0 to 3 months and it fit her perfectly so the question im trying to ask is what size should i buy her if i go to carters?