Trying to get milk back

My son will be 3 months old in a few days, when he was born he was allergic to dairy in the formula that he was given I really wanted to breastfeed but had difficulty getting him latched. So I started pumping once I was home and at that time my son was pooping large amounts of blood from the formula I had given him. His pediatrician told me to hold off on giving him my breastmilk until they made sure he was okay. Once they found out it was a milk protein allergy they encouraging me to stick to the type of formula they put him on and to not breastfeed him, they ( the two pediatricians in the office) that if i eat dairy he will still be sick. So i stopped pumping and let my breast dry up. I still had a supply in my freezer so my husband and I decided to give it a try and see how he handles it. My question is if he handles it really good would i be able to get my milk back?