How much to feed Pug per day?

Hi everyone! We just adopted a female Pug that was rescued from a puppy mill situation. She currently weighs 19 pounds. She is 3 and has had several litters of puppies in the past. She is spayed now also. We're feeding PPP and the bag recommendations for servings seems a little high, but I'm no expert. The food has 400 k as calories for a serving. Can you help me figure out how much to feed her per day? She eats twice a day. Thanks in advance!