P.B.
why the need to use a sippy cup so soon? What about a bottle that is similar to a breast......I've seen two different bottles that are "shaped and feel" like the breast. I think one is from the catalog "One Step Ahead" and I think the other one I saw on "Mothering" magazine website....It's worth ordering one of each and see if he'll take expressed milk from one of those bottles.
Your employer should allow you extra time to pump milk at work until you find a formula that your son seems to like.
Carnation Good Start with the broken down proteins was the only one my kids, (who were all breast fed), would take....in fact, I did not go to whole cow's milk until my kids were 2 or 3.....I used the Carnation formula all that time.....cow's milk made them constipated and sick, so I just used the Good Start formula until they could handle milk. It was better for them anyway than the cow's milk!
Pam