There are many lessons here, including some we may already know and are worth repeating:
Always phone reservations for changes, even if it means a toll-call to the US.
Re-book on the first flight out (in the case of the poster, to BOS at 9am), even if you know you may not make it. Once booked, you "trump" the passengers later in the day. And early-day flights always fare better than late-day flights.
And keep a positive attitude. American has many talented people who will try to help, but you have to understand the methodology of the systems behind the scenes that compute the terms of travel in order to understand what you can expect during difficult operational episodes.