My 13mo DD has acid reflux and has been on Omeprazole (switches off stomach acid production) since before we started weaning (after both gaviscon and ranitadine failed). She's been on lactulose for nearly as long as the omeprazole to counteract the constipation it causes. We dropped most of her milk feeds at 6 months (under medical advisement) since it's the milk that mainly comes back up and went down to just morning and bedtime but had to reintroduce mid afternoon milk to make sure she got enough liquid into her to stop her getting so constipated.
We've only ever given her aptamil comfort formula, she does have cows milk on cereal and in cooked food but I'm very wary of giving it to her as a main drink since it's often a problem for reflux babies. I was thinking about moving her on to a toddler formula, she's not been sleeping as well and I was thinking it might fill her up a bit more at bedtime. Also her body's never been given the chance to process food properly so I think that the extra vitamins and iron might not be a bad idea. We are having trouble getting her to finish her bedtime milk too, we still use a number 2 teat (up to 6 months) because every time we tried a number 3 she drank the milk too quickly and it came straight back up again, but it may be time to give it another go.