Sorry to say but I think you should stay home. I have made two trips cross country with my son lately one at 14 months where we flew alone and the other at 16months with my husband both where terrible! Now granted my son was an angel flying as an infant but a few months makes a world of difference. Think about how hard it is to take a toddler to a restaurant, they have short attention spans, and cannot stay seated for long, now multiply that by several HOURS. Do you really want to put all that stress on yourself and your sweet little girl. Do not fool yourself that she will sleep, she may or may not. And as for the car seat thing, I hauled that sucker around in vain hoping to use it but contrary to what the ticket agent told us most airlines will only let you use seats if you have purchased a ticket for your child (even if the flight is not full!)Our trip was to visit family we had a great time while there but, we went for a month the first time, my son slept with me every nighteven though there was a perfectly good pack n play for him to sleep in. The second time for two weeks. He did not adjust to being away from home and getting him back into the routine
once we returned was not fun either. Other things to think about, Luggage, toys, child proofing this house, eating situations( food, highchair, Bottles, cups)diaper supplies, total change of climate and clothing issues. How much help will your man be to you while you are there and what kind of prenatal care will be available? Really, you and your girl are better off staying home. Make it special time for just the girls before the baby. My spouse is in the military a couple weeks or even a few months will go by faster if you are in familiar surroundings, make videos and phone calls often. It will be okay!
L.