What does it mean when a flight attendant will tell you once on the plane that you’ll need to check the bag at the gate? Does that mean going all the way back to before security to pay for a checked bag? How will you get that done in time as once they allow passengers on the plane the plane normally departs within 10-15 minutes, which is certainly not enough time to get back to the checked baggage area.
You likely have not flown with many infants (and strollers). If you have a stroller, you fold it up and leave it right outside the boarding door on the boarding ramp. They always tell you/remind you to do that when they take/check your ticket at the boarding gate. Your stroller is waiting for you just outside the plane’s exit door as you later disembark.
The hysterical woman, who may have limited English proficiency based on her accent, may have not understood that and went directly on the plane with it. Before any smart ass asks me if I was on the plane that’s just an educated guess on my part based upon my experience.
They make you catch the next flight.