When my DD was 13 months we did the following......
Took a portable DVD player for her to watch off an on (at this age they don't watch it like older kids, but at least it's something for her to watch).
Took many many of her favorite snacks
Took many books for me to read
Took favorite stuffed animals
Prayed and prayed that she would fall asleep during the flight
Actually, my DD was very sick the day we left (103 fever) and we had no idea why. Even my Pediatrician didn't know, because she wasn't sick long enough to make a diagnosis. So I did all these things, and prayed that her illness didn't escalate to vomiting and diaherrea, which it didn't thank God!!!!! All I know, is my carryon was busting at the seams between all the stuff and for both of my girls, and medicianes. The security guard even searched the bag after we went through security, because he said, "There's alot going on in that bag"

He was very nice about it, and tried to not make a mess - everything was very organzied.
Good luck, it's a challenge, but if you go prepared, you'll be fine
