This is for a domestic flight on AA metal.

If I book an "infant" award with my avios, its charges me 10% of the miles for her ticket, but it allows me to select flights that only have 2 seats available (me, wife, and infant traveling) which leads me to believe I'm getting charged 10% for a lap child (which is free on AA.) So, do I have to book an adult award ticket so that she gets her own seat? Will it even let me?

I do not want to have a lap infant. I would prefer getting her her own seat, but cheapest way possible.