I swear Delta never boarded my flight

I feel like I’m going insane. I was supposed to fly from ATL to MSN last night on DL2144. The flight was delayed several times. I was at the gate the entire time - it was finally supposed to leave at 11:17. At 11 I texted my husband, “There’s no way this plane is leaving, they haven’t even started boarding yet.” I sat there until 11:40 when I noticed that the area had cleared out (there was a flight across from us and a lot of people at my gate got on it). then I noticed that Madison was no longer on the gate video screen. I found a gate agent and they said the plane left.

But… what?? How?? I was sitting right there. I did not have headphones in. Is it possible they would have done boarding without making any announcements or calling any zones? I didn’t get any text or app notifications about boarding either. I did have my back to the gate but I was five feet away. I guess the reason could just be that I’m a total idiot, but … what about final boarding call? What about any kind of announcement of any kind?

Has anyone experienced this because I feel totally nuts.