I keep asking myself this about my stash! I will be primarily using prefolds as well, I have 24 infant sized now, but I also got:
6 kissaluv size 0 and
2 or 3 other fitted newborn/ small dipes
for those first few weeks/ months.
I got 5 of the kissaluvs used here on the TP and bought 1 brand spankin new one
I also have a few more covers then you -
like 8 PUL nb covers (proraps, bummis and very babys)
1 nb fleece loveybum
1 small fleece stacinator
2 nb/ small wool soakers.
Also a handful of small sized PUL covers - I dont have any mediums yet.
Oh, and I decided to get some preemie sized prefolds *just-in-case.* I have 5right now, but will prol get a few more.