Transdev told the Herald last week Ms Johnson had "not communicated very clearly that she wanted to get on the train as well, or that there was an issue".
But after seeing the CCTV footage herself, Ms Johnson was convinced that she had tried hard to get the attention of the conductor.
"I was yelling, you can see my lips moving," she said.
"I turned sideways, my arms are out like 'Come on, open the door', swearing, walking towards the train. You could tell I wanted to get on the train."
The footage did not show the conductor so it was still "his word against mine", Ms Johnson said.
"I just said to them, 'All I wanted was an apology and now you've given that to me I'm happy'."
She said she would avoid trying to board the train while the doors were closing in future and would try to be on time.
Transdev spokeswoman Brooke Donovan said company bosses met with Ms Johnson and her parents yesterday. "We have absolutely apologised to Jamie-Lee for the frightening experience she had on the train, and we know that's a scary thing to happen to a parent."
She reminded parents to ensure they stayed close to their children at all times at stations and around trains, arrived early before boarding time and did not try to move through closing doors or while the door alarms were sounding.