Hi there,
First, I wouldn't go with soy milk, they are saying now that soy isn't good for females due to the estrogen in it. Natural soy is ok like edamame, processed soy is not good. (vegetarian products). They also hide soy in frozen foods too.
She doesn't even need milk, you can give her cheese, yogurt, cottage cheese or any other product that has calcium.
If you want milk for cereal, then the Rice milk or Almond milk would work just fine.
Both my daughters have food allergies. My 4 year old has allergies to wheat mostly, which you can imagine is a pain in the butt. But, my 1 year old has allergies to wheat, eggs, soy (very mild) walnuts and peanuts. I had a blood test done for my baby. She itched like mad when I gave her eggs and wheat for the first time. Those two I knew she was allergic to before I got her test done. My 4 year old ends up with eczema when she eat too much wheat. Thankfully, I do not have any milk issues.
Anyway, as far as nursing goes, I would just move on and fix those nipples!!!!
Take care!!!