from about 9 months i put my DS1 on full strength cows milk due to living 30-40min drive into town (we have local shops but exspensive plus they didnt stock the formula i used and not open for very long hours) He didnt have any reaction to it so i think you did a good thing

my 4.5 month old just had cows milk over easter weekend cause i didnt realise i'd need a new tin of formula before the public holidays eneded so he had to have 2 bottles of cows milk, didnt harm him either...

i also wanted to BF for this same reason but didnt get a chance to do it for very long unfortently