After 12 months, milk is not necessary, but if you cut out dairy and other milks you will need to make sure there is enough calcium in her diet. This site gives you a good idea of other foods that have calcium in them - Vegetarian Network Victoria - Complete Nutrient Summary. It is certainly possible but many mums do find that dairy or another milk make it easier to reach the daily requirement.

I totally agree with getting professional advice. Dieticians are best place to help with food sensitivity issues - they usually have done 5 years of study to become qualified and doctors have often done just 4 hours of nutrition stuff as part of their course. A good place to start is this website, Dietitians Association of Australia (DAA) : Find an APD, searching for Allergy and food sensitivity in the Area of Practice. Because you are also still breastfeeding you might want to also search for Breastfeeding as an area of practice and find one who does both. That way you can get good advice on your own diet while breastfeeding and eliminating foods in your DD's diet. If you don't find any near you, some do Skype consultations. I can highly recommend one dietician who works across both areas - PM me if you would like her details.