Will my baby still grow healthy on soy formula?

my little girl is 3 weeks old. im on wic and at the hospital they started her on goodstart gentle plus formula because thats what wic will cover. well shes been acting really uncomfortable while drinking it and she acts like shes in pain the whole time. she only pooped once a day. the doctor suggested soy formula, so he gave me a sample of emfamil soy formula. he said if that seems to make her feel better then goodstart soy should work just fine. ive had her on it for two days and to me she seems like shes burping better, spitting up less, and she falls asleep faster and doesnt act like shes in pain. but ive been reading not to put them on soy unless they really need it. i just want her to grow healthy and strong. did your baby grow just fine on soy formula? the reason i was worried is my friends take their little girl to the same doc as mine goes to and she was having the same problem and my friend asked if they should switch to soy and he told them no. i wonder why he suggested soy for my girl then?