7 month olds barely have a routine anyway. You and she will be fine. I know it seems daunting the first time, but the more you do it the less daunting it will be. Bring an extra change of clothes for you and her for the plane, lots of diapers and wipes and some disposable changing pads, a few toys, and a bottle or pacifier or something for her to suck on. Gate check your stroller.