FIRST TIME MOM

HELP, my daughter is about to be 2 weeks old. She was drinking Similac at the hospital but once I got Wic they gave me Enfamil the yellow can ever since then she hasn't poop. So Yesterday i switch it to the gente lease formula still hasn't poop. I have tried the karo syrup she only had one dirty diaper basically diarrhea. I don't know if that's normal or what to do??