My ds has a lactose sensitivity as he gets it from me, i am lactose intollerant. He was on soy and others for a bit but the lactose free formula worked best, should i try reg formula soon? or should i just wait till he will be intoducing to cows milk and slowly into him into tat. i just don't want to mess with his system anymoe if i don't have to plus he has never been a good sleeper and i don't want the nights disutbed more with a upset tummy. when do most do the switch? he is 5.5 month.