She is only 2 and she weighs 70 lbs she has black gums and brown eyes the white part please help.

70 pounds sounds pretty big to me, why do you want her to gain?
Has your vet told you she is too thin for her stature.
I'm also not sure where the gums and brown eyes come into play, was there something else you wanted to ask?

I will agree with Lady Sam, 70lbs seems like a healthy weight for that mix. She may ger her girth in her second year, but anything over 70 lbs could cause harm to her joints and ligaments. A leaner dog tends to be a healthier dog.

Any chance of posting a photo of the dog so we can see her current weight?

A photo side on and a view straight down on her back would be great.

When you look down on a dog over their back you should see the curve of the ribs and then their body taper inwards slightly before going back out to the hips.
You should be able to feel rib without pressing too hard on the dogs sides and for short coated breeds the last few ribs should be visible when the dog is in motion.



http://sportsandfitness1.com/wp-content/uploads/2011/12/Dog-Weight-Chart1.jpg