You don't say what breed she is, but I would stick to the Burns guidelines unless YOU think that your pup should have more weight. Vets seem to go by charts and we all know how accurate the AVERAGE weight charts aren't ;)
Panacur, like all wormers, can make the stool a little looser (or in some pups a lot ;)

) but there's no need to starve your pup, a little Bio Yoghurt should sort this looseness out in a few days :)