Fuzzi Bunz Sizes

I would say, yes
my ds is almost 14 months and 22 lbs and he fits into a medium on the second tightest snaps, so I think a medium would be huge on your baby girl right now.

and in general, we love them
we have been using them for about 6-7 months and we've never had a leak or any other trouble with them. We use joey bunz as inserts, but we have a few of the microfiber MOE inserts and they work great as well.

Small sounds perfect for you. I have found the sizes to be kind of all over the place. I didn't really notice with the smalls, but I have mediums that are bigger than some larges
I think they work great for night especially, they are easy to stuff and since there is no elastic on the fleece at the pocket opening, it's really easy to just shake out the stuffer.
-Nicole