So my period began again at 4 months post partum. I've noticed a significant drop in breastmilk supply since that time - particularly when I'm pumping. I have to travel without baby in about a month and am quite concerned that I won't be able to build up enough of a stash between now and then. So, here we are at 6 months and I thought I'd give supplementing with formula a try. I gave him 2 oz of breastmilk and 1 ounce of formula (enfamil supplement) at 4pm. Since then(it's now 8pm... I breast fed around 6, as well), he's been gagging and spitting up way more than usual. Help! Do I just need to give him more time to adjust? Do I try another brand or type of formula? Not sure what to do from here...