They say give it a week and formula switch can definitely throw her off if she isn't crying like crazy she's fine also warm baths and tummy rubs help this early on
I was told going 2 days without a bowel movement can be normal but just rub her back downwards and burp her, keep her fed, switching formulas can cause a temporary back up from what I've always heard.
Then just monitor her. I know that babies can go a day or two with out pooping I forgot how long for formula fed babies but if you are worried you can always try her doctors they'll most likely give her a suppository