Overnight Diapers?

Well it seems our reliable overnight diapers, Pampers Babydry, are no longer working. Olivia wears a size 4 and we've been using Pampers Babydry as her diaper for all day and all night, even though it is supposedly an "overnight diaper" only (what is the point of two different diapers for one baby?). As of a few days ago, she began waking up soaking wet in the morning. This troubles me because not only is she sleeping in #1 but there is also more laundry for me to deal with. Now the question is do I try to find a different type diaper for her to use overnight or try going up a size for nighttime? I really hate the idea of two different diapers for one baby but I hate extra laundry more. Would a size 5 diaper have more absorption or would it just be roomier? I also read online someone recommended putting a women's menstral pad horizontally across the top of the diaper during the night. That will be a last resort to try though... Any suggestions?