I wouldn't worry too much about the dog's actual weight at this point. How does the dog look? Are ribs clearly visible? If so, your puppy might be too thin. If you look at your puppy from above, can you see a definite waistline? If you run your hands along the dog's back and sides, is there a thin layer of fat? There should be - you should be able to feel the ribs without having to dig in, but you shouldn't be able to see them.
When puppies are young, up to about 6 months, I will generally feed them as much as they'll eat. I find that most puppies aren't total gluttons at that age yet, and will eat just as much as they need, and not too much more. Even if puppy seems a little bit fat at this age, I don't worry. If puppy still seems hungry at the end of a meal, offer more food and see if she takes it. If so, give her another 1/2 cup or whatever and let her eat it if she wants to.
Also, she should be eating at least twice a day . . . three times a day if you can manage it. Up until the age of 6 months, I try to feed my puppies three times a day, and then I go to twice daily feedings.
Can't wait to see some pictures!