Hi kayla:
The first time I flew with my baby alone (without any traveling companion) was when Junior was 7 weeks old, from HKG non-stop to L.A. Needless to say, I was very scared. Almost 2 years on, and precisely 50 flights later, I now realize that that was one of the easiest flights with him!
I don't want to make you worry too much, but honestly an 11-month-old can be quite handful in-flight. He now can move about and wants to do just that. I totally prefer an aisle seat, so at least I can let him stand in the aisle every now and then while I myself am seated in my seat holding onto him. It's also easier to get in and out during the flight.
I ALWAYS change him in the washroom, standing up. I think I've learnt to master that... Give him something (a toy) to hold, so his hands won't be touching anything he shouldn't be touching.
Any food you bring that needs to be chilled can be given to a flight attendant when you board (which normally is before most other passengers). Make sure you write your seat number on it. Not every airline has a microwave oven, so heating up can be tricky. I normally stick with foods that can be eaten at room temperature or cold. Whatever food that can be packed in a zip lock bag, goes in a zip lock bag. That way you can just throw the bags away rather than lugging some empty containers along everywhere.
When your baby is sleeping, and you need to use the washroom, please ask a flight attendant to keep an eye on your baby. They are more than happy to help. Some times they even offer to take your baby for a walk. Let them. You need every breather you can get. One very important thing.. when he sleeps, you sleep. Forget about that movie you have always wanted to watch... You never know when you'll get to sleep next.
Inevitably, babies do cry at times. Just be calm. I know other passengers hate it, but so do you. I'm sorry to say, but how your baby feels is more important than what other people think of you. Just concentrate on making him comfortable, and both of you will be fine.
Last but probably most important, try your luck when checking in. Do ask whether it's possible to get an empty seat next to you. Cathay Pacific and Air Canada have been great at entertaining the request. I guess most passengers would like to be away from babies anyway.
Good luck, kayla. I'm sure you'll be fine.