Hmmm...there really is no way to "put some weight on her before she is ready." What you need to realize is that it's not the weight of the dog, it's the size and structure...two different aspects. Sure you could put weight on her--you could over feed her and she could potentially be overweight and tip the scale past the 5lb mark. But that won't mean she's "ready," as you put it. When determining if it's safe to breed a female, you have to look at size and structure, not neccessarily just weight. Make sense? This is one of many reasons why people often wait and acquire their breeding stock when the pup is older.
Basically, she's either going to be big enough, or she isn't. It's going to come down to genetics and how she develops as she gets older. There isn't anything
you can do yourself to change it...nothing you can do to ensure she reaches the appropriate size for being a brood bitch.
Keep in mind, "the charts" are just a rough guesstimate--they are not set in stone. You may get lucky.
