I think shes getting around 4 1/2 to 5 C a day. She never really finishes a meal, so I leave it down and she snacks. When we hit the vet tomorrow to get her ears taken down I'll ask about her weight
If she doesn't finish meals I'd not leave the food down. It's a generally bad policy. It ends up being free feeding and doing that can end up in a number of ways--all pretty unsatisfactory. Either you get a dog who habitually overeats or one who is incredibly picky and undereats. And worse you don't have the advantage of the heads up of a dog who eats normally finishes all meals in a short time going off their food which is often the first sign that something is wrong.
Also if she's getting 1/2 to 1 cup of food in the form of treats I think I'd start giving smaller treats. A treat to a dog is a treat whether it's huge or very small. For training purposed I rarely give treats bigger than 1/4" square. I want them to eat meals and not hold out for "treats".
Also you should probably remember that puppies when growing quickly tend to go through phases. First they will look roley poley and fat and then go through a growth spurt and look like they are nothing but legs and peanut bodies. She's probably getting enough food but at 9 weeks even I who drop the third meal pretty early usually feed three meals until they are around 16 weeks old.
Typically you count weeks as weeks and months as months. On average months equal 4.3 weeks. So if you say that your puppy is 9 weeks it would work out to about 8.6 weeks.
But since she's going in to the vet anyway check with the vet to see how they feel the puppy looks. When it's all said and done I look at my dogs daily when I'm feeding them from they time they are puppies and adjust their food according to how I think they look. Works for me--harder sometimes to pin it down on a growing puppy because of the stages they go through with the growth spurts. I have no idea what the average weight is by the month for most puppy bitches. With dogs from two to six month you expect the dog to weigh about 10 pounds X his age in months. So a two month old male puppy would be around 20 pounds and a four month old would normally be about 40 pounds. And at the mid points of the months they've usually added about 1/2 or the weight they will weigh at the next month.
Puppy bitches will weight less but since I don't raise puppy bitches I don't have as good a feel for appropriate weight at a given time.
Good luck...puppies are resiliant--they can deal with errors--just remember to keep upping the quantity of food as she grows.