6 months old female grouth

Question
I have a 6 months old female lab. My question is how much height and weight it is suppose to be. Now it is in between 17 to 18 inches. Is it correct height? I never measured about weight, but comparatively it is thin. Can you suggest me what type of food I can give her and how much quantity it requires? Please

Answer
The first step is to evaluate her as in this link, http://www.longliveyourdog.com/twoplus/RateYourDog.aspx  If she is too thin by that method, just feed her a little more than you have been.  Most Labs need about 3-4 cups of food and will do fine on all but the cheapest dry kibbles.  I have seen thousands doing very well on Pro Plan chicken and rice.  

Labs vary in size.  I have a fine little year old one that is only a lean 47 pounds. Some may be 80 pounds and still be lean and healthy.  You can find breed standards for size for Labs at www.akc.org, but they are only important for show.