To the OP, can you take your pump and pump while you drive and give her that? I did that with a trip we had - only 8 hrs - so we didn't have to stop to nurse. :oops: I just kept my ISIS in a chill bag and reused it, washed it when we got there. He was old enough I wasn't too worried about the cleanliness factor.
My guess is AF will arrive any day. If you have been stressed about your trip, that can affect supply too. You are busy packing and doing the extras, you forget to take care of you.
To the other poster, some moms get to a point when they don't feel a letdown, although if you are suddenly not feeling it, it could be supply related. Usually more frequent pumping/nursing can increase your supply, along with extra water and adequate calorie intake. Have you been dieting or exercising? Has AF returned yet?
I would first try making sure you have adequate meals/snacks, at least 3 32oz waters per day (limit pop as it dehydrates you), and pumping once (or twice if you can swing it) extra feeds. So if you nurse 3 times and pump twice, add an extra pumping (or two) or feeding. (If you CAN go to nurse, that eliminates the formula question at daycare) Make your body think it is a growth spurt. Do this for 4-7 days depending on results. This is what worked for me with my ds. If after a week you are still not getting the results, then we can talk supplements.