Milk issue again

I forgot to mention that when we went for the babies check up I was talking to the nurse about Preston's milk/tummy issues. She said that I should go to lactose free instead of soy. That more than likely he isn't having an issue with dairy since he tolerates cheese, yogurt, ice cream and other things with milk. She said that soy doesn't have as much calcium and that soy isn't milk at all. I knew that but figured since they were on soy formula than soy milk would be fine. So we are going to try lactose free until 18 months then try whole milk again. She said sometimes babies born early can have stomach issues when switching to whole milk. Eventually I am sure he will grow out of it.