I noticed this morning that AA’s web site once again allows you to pre-order meals on future flights within the next 30 days. A useful feature, it went missing from the web site when AA/US’s merged web sites.
Look up your reservation and look for this link:
You then get a link to the flights in your booking where you can pick your meal:
These items are the meals that will be loaded for the flight and the crew manifest will tell them you have pre-ordered. They usually come round and confirm your preference and I have never been unable to secure the meal selected online.