Don't give up. The chances are very good that your bag will show up eventually. IIRC AA should reimburse for approximately $50 worth of toiletries/necessities. Be sure to keep receipts.

As to how your bag could be lost, there are soooo many possibilities. Sometimes bags get sent to wrong detination, and sometimes they fail to get sent anywhere at all. They can fall off the cart, every now and again entire carts don't get loaded, and sometimes they are off-loaded because of weight issues (doubt that's what happened to the OP though). If you can imagine it, it's probably happened to someone's luggage.

The worst part is that no matter what the cause, it is so frustrating as a pax when checked baggage goes AWOL. I can really empathize with the OP.

Good luck with this and I hope that bag shows up soon. (FWIW I have not seen your bag anywhere in the North Texas area. )