Aiyoh don't worry too much, my neighbour's baby also went through same thing when she switched formula, her PD told her the tummy adjustment can take up to 2 weeks, so a bit of hard stool or less pooping is quite normal at first. Someone in my mum WhatsApp group mentioned switching to Nan Pro helped her baby cos it's gentler on the tummy, and she made sure to give extra water sips too. But since your baby is a newborn and you also just stopped breastmilk at the same time, better bring her to see her PD just to be safe ya!