I don’t know what to do.. please help

My daughter is just about to turn one, she is on nutramigen formula because she wasn’t gaining weight and very loose stools and puking with the regular formula. Anyways her doctor said to give her whole milk as soon as she one, and if she has a problem with it then they will say she has a true cows milk allergy. Just giving her something like mash potatoes with 2% milk makes her belly upset and she gets loose stools and pukes that smells like sour milk. Her grandma gave her pumpkin cheese cake firming thanksgiving without me knowing it was cheese cake, and she puked that up with sour milk smell as well. So I follow what the doctor says or should I just put her on almond milk?