I flew with my son at 3 months and again at 6 months. (he's 4 now and has flown several more times).
For the flight I bought one of those nursing shawl things that actually goes over your head like a poncho so I didn't have to worry about him pulling the blanket off and making other passengers uncomfortable. Also, I had a black one which helped make a little safe low-stimuli place for him to relax under there.
Beyond just feeding, nursing on take off and landing will help keep her ears clear (the infant equivalent of chewing gum or yawning), and will help her feel safe and secure in what could be a confusing experience.
If your daughter will take a bottle with expressed milk, you might want to pack one in your carry on (breast milk can be unrefrigerated for like 10 hours or so with now worries) just in case she needs to be fed at an awkward moment (ie lining up to board, getting off of the plane, moving from one gate to another).
Oh, also for diaper changes, most plane bathrooms actually have a pull down changing table in there. It's cramped, but it works, so check it out. It's usually over the toilet so you stand with your back to the door.
HTH
T.