Welcome!! Thanks for starting out with the beautiful pictures of Lexi. We have lots of forums on food, and we all have different opinions, so you will need to make your own decision on what food is best. In order to figure out how much food you should feed Lexi, you need to know how old she is, her current weight, and what kind of dog food you use. The information on the bag of dog food you bought well give you an idea, but usually shelties should eat less than what they recommend on the bag. Best way to tell if she's getting the right amount of food is to check that you can lightly feel her ribs, if you can feel the bones too easily then she is underfed. Another easy way to tell, after you have had her on the same food for about a week, check her stool. If it is firm that's good, if it is too loose then she is eating to much for her at this time, and if she has diarrhea then she is eating way too much food. Congratulations on your new furbaby.