Gaaaagh my brain hurts (size v onesize)

AGFaso

Which ones (brands) are one size and which are "sized"--> Nevermind

Sorry in advance.  I'm trying to figure this out!  I've been to Jillians drawers but find it to be much cheaper on E bay but I need to know exactly what I'm lookin for, kwim?

ETA-My brain still hurts and idk what to do.  Idk what kind to buy or from which site.  Ebay seems to have some pretty inexpensive ones.  

I'm having twins, they are going to be small, probably for a while. So I am "watching" some Kissaluvs size 0 newborn cloth diapers and some no names cloth diapers for newborns.  Should I get the preemie ones??

I dont wanna buy cute covers yet bec idk the sexes of the babies yet.

Pointless rant.  Advice still welcome.  Ignore if I'm annoying.