My dd has a milk protein allergy, was diagnosed at about 6 weeks of age (had blood in her stool). I, too, have had to eliminate all dairy. My doc told me to take a calcium supplement, I use either the chew ones or the chalky pill ones, they are fine to take as they are calcium and not milk product made (exception is the chews- check the ingredients of different flavours). I also went on line to find out what foods are higher in calcium so that I can focus on these to eat.
Once your lo is older and on solids be careful of the cereals- some contain milk products. I asked my ped about calcium deficiency as my dd cannot eat yogurt, etc, and the quantity of bfs are less now, she said she's never seen a baby with a calcium def so not to worry too much if you continue to bf.
I use rice and/or almond milk myself, just a suggestion if you can't continue with the soy. There's a great post on the allergy board on MPI which has a list you can print out and carry with you to help determine which items fall under the milk product catagory.
