All "We" has to mean is her and at least one other unspecified person.
In her interview Westbrook refers to herself and her work colleagues collectively over and over again. Here are a handful of examples, there are many more:
"...and because it was towards the end of the parade
we knew that
we could go down a little bit close to the underpass...
we could stand directly on the kerb and get a first-hand view."
"...the car kind of came a little bit closer to the kerb where
we were standing."
"...
we were waving and screaming and so excited."
"
We were on the kerb here, and she was leaning over the President and pulling her hair out of her eyes as they were waving to
us,"
She is clearly referring to herself and her work colleagues. It is unreasonable to assume otherwise.
Sorry, no. She doesn't say that she returned to the building during the "pandemonium".
"...there was a quiet calm while the shots were fired and then, when everybody realised the shots were fired, the car sped on, then it erupted in pandemonium and everybody started running every place, so
we came back to the building..."
We're definitely going to have to disagree on that.