Hi K.,
My daughter was just diagnosed with the same thing. She's 6 months old and breastfed, so I have had to cut dairy from my diet. I have yet to meet with the nutritionist, but my pediatrician has been helping me with the diet part. My pediatrician's son also had the same allergy and she too had to cut out dairy from her diet, so she is knowledgeable on the subject. I'll share a little of what she told me and it may help you too. She explained that to start with, I did not need to cut out all dairy, just the most obvious sources of dairy such as milk, cottage cheese, sour cream, ice cream, etc. I did not need to cut out bread because the milk in it is de-natured and will not harm the baby. She also said that hard cheese is generally okay, but I had to watch the baby to make sure she did not react to it. As for soy, not all babies who have a milk protein allergy are allergic to soy. There is cross-reactivity but some babies do fine with soy. My doctor encouraged me to try soy and see how my baby reacts. My baby was having bloody stools but now with this diet, her stools are normal.
Having said all this, I would say that you may have already established that your baby's allergy is severe enough that you need to cut out all sources of dairy plus soy, and if so, I apologize for the long note :) Also, since I'm not a doctor, I may be giving you advice that's wrong for your child, so pls take my advice with a grain of salt. Good luck and let's both hope our kids grow out of this!!