Are these normal feeding habits?

My cat never finishes her food in one sitting, is this normal? We adopted her in November, they gave us a ziplock bag of the food she was eating to give at home until we can go buy some. It said 1/3 twice a day. So we’ve been giving her 1/3 in the morning when she wakes up, and 1/3 at night. But she never finishes her food in one sitting. Even though she gets excited when we bring out the bag of food, and replenish it. She just comes, and eats small portions throughout the day. Never fully finishing her food. She does however finish her water bowl, we refill it throughout the day. She’s also our first cat ever. Will take any advice.