Hi A.---I tend to agree that it is probably something that you are eating. You could probably do an internet search of the biggest offenders, and cows milk is probably at the top of the list. (For more info on the dangers of cows milk, go to www.strongbones.org) Then start to exclude those from your diet one by one to find the offending food. It is likely to be a temporary sensitivity. The one thing I realized about having babies is that once you think you have things figured out and a routine established, they move into another developmental stage and you have to start figuring things out all over again.
Based on your post, it doesn't sound like she is in great distress all of the time, so try not to worry too much unless she develops fevers or changes in bowel habits.
It's been a long time since I had babies, so I'm not sure what is available, but if you can find a formula based on goats milk, I understand that it is most like human milk.
Good luck. I think the biggest challenge will be to try and be patient, even in the face of a little discomfort, for your daughter's body to adjust to having to digest food on her own.
It will happen. Just be confident in knowing you are trying to do the best and that she is extremely resilient. In health, D.