If you are comfortable holding her during take off and landing, then nurse her. I am freakish about the baby needing to be in
the car seat, especially for take off and landing, so that was tough for me. Two of my babies took a pacifier, so no problem, but the other one wouldn't. Here's one more option, will she suck on your finger? All of my babies would. I know it might not be the most sanitary thing, but I would wash my hands, and just use it in a jam. If you haven't tried it, use your pinky finger, turned bottom side up (nail on the tongue, not on the roof of the mouth). Maybe that will help! (Maybe sippy cup, too....my kids all started a sippy cup around 6 months).
Good luck!