[LMILEO]

Booked flights on Expedia 3 weeks prior.

Dec. 1, AA4057 cancelled, not notified, but checked on my own and rebooked myself on AA4058..checked in online with boarding pass and seat assignment. Boarded plane and right before door closed I was removed from plane due to "plane weight issues". I'm 180 lbs, that makes or breaks a flight weight issue? There were 5 empty seats! Upon removal, I was told at gate I was "volunteered" because I purchased a discount seat from a third party and due to that fact, I was merely "wait listed" on the flight... Really? So beware, if you purchase from Expedia, don't expect a confirmed seat, even with a boarding pass and seat assignment!

[Burgers]

When you buy tickets from Expedia, Orbitz, etc that's your travel agent, all fine till its not. Its always advisable to buy directly from the airlines website. When you purchase from a ticket consolidator you are buying at the lowest fare bucket, you'll be the first to be denied boarded.
As far as being offloaded from the flight its because of a federal government rule that allows airlines to deny board for safety reasons aircraft under 60 seats. Yes, your 180 lbs makes a difference.