I think Evan is nearing that age where he can start communicating through sign (amz). He effective has started using his own sign for "pick me up" which is a natural gesture of simultaneously raising his arms above his head and holding them there. As long as we reinforce the sign by picking him up when he does it, the sign will stick.
Cathy and I prefer to teach ASL over made up signs but are flexible enough to adapt to Evan’s own choices. The trick is to pick a single sign, like banana, and use it until the child learns it then add another sign. Trying to teach too many signs at once will only lead to frustration. With Amy it was very nice to know that she wasn’t just hungry but that she wanted a banana or apple juice before she could speak.
Other posts referencing Amy and signing: