Whole Family: Infant, Enfamil

Going on Vacation - Not Enough Milk

I need help! I'm still breastfeeding my 7mo daughter (plan on continuing for a long time!), but I'm going on vacation without her soon and am worried I don't have enough milk stored. I've been pumping like crazy - but I'm very fearful I'll be a little short. Should I mix formula and BM half and half? Should I introduce formula before I go? Will it be hard on her system to handle both? I have no idea what to do! It's hard enough leaving her....