She will be fine newborn milk is a tad bit more sensitive but if baby is not throwing up or anything, she’s fine I would breast-feed her a little bit more maybe pump in a bottle
The difference between them is the type of protein that is used. First stage infant milk's are predominately whey protein and second stage infant milks – marketed for hungrier babies, contain more casein protein.
She should be fine. Those milks for older kids are pointless anyway and just to make more money. I think the only difference is it might have more calories or something sooo it should be good.