FWIW, the AAP and WHO recommend breastfeeding for up to two years old or older, if possible.
Not sure what the recommendations are re: formula.
I just weaned my 15 month old since he started daycare. I wanted to go up to 18 months but it was difficult to wean, sleep train and prepare for daycare all at once so it was quite gradual until one day he didn't grab at my chest anymore.
FWIW, the AAP and WHO recommend breastfeeding for up to two years old or older, if possible. Not sure what the recommendations are re: formula.