The Kissaluvs website has a fabulous "fit matrix" page with all sorts of info about what covers work with their diapers:
http://www.kissaluvs.com/diapercoversmatrix.htm
I think they recommend that you size up on Bummis covers. I've been successfully using medium Bummis snap covers with my size 2 Kissaluvs on my 14-19 lb. dd (I bought large), but we'll be sizing up well before she reaches the 30 lbs. that the Bummis Med is supposed to cover.
HTH!
http://www.kissaluvs.com/diapercoversmatrix.htm
I think they recommend that you size up on Bummis covers. I've been successfully using medium Bummis snap covers with my size 2 Kissaluvs on my 14-19 lb. dd (I bought large), but we'll be sizing up well before she reaches the 30 lbs. that the Bummis Med is supposed to cover.
HTH!