My daughter will be 6 months tomorrow and I’m weaning myself off of EP. I still have a decent stash to be giving her only breast milk for a little while, but will be moving to formula. I have 3 questions:

1) I still have premade formula bottles from the hospital that say they’re good until December- do I trust that?

2) the sample containers I have say infant formula 0-12 months. Are there formulas that are more age specific or is that the general age range?

3) is it important to stick to one brand? I have both similac and enfamil sample containers and coupons. Is it ok to switch it up/use both or will that mess with her tummy.

Thanks for any and all help!