The Cork contestant was sent home after failing to shine in a rooftop photo shoot with Rizzle Kicks, ending up in the bottom two with Maddie, who was saved by judges because of her popularity with the client.
Speaking to Digital Spy afterwards, Kellie admitted that she had been "quite shocked" by her exit, as she felt this week's picture had been her "best one so far".
"I didn't really like my Paris shoot, I thought it was much stronger than that," she said. "[But] because I knew that Maddie was really loved by the client when it was Maddie and me in the bottom two I knew I was going home."
The 21-year-old went on to recall feeling "really nervous" and "intimidated" by Rizzle Kicks during the shoot and said that she would come into Top Model with more confidence if she could redo the experience.
"I knew I struggled a lot with my nerves," she said. "I was so, so shell-shocked. I was taken out of everything I've ever known.
"I never thought that someone from my background could be on one of these shows and growing up watching Top Model I never thought I could be one of those girls.
"In this game confidence is key. There is no room for doubt and I felt like I did hold back a lot and I could have done a lot more. If I'd stayed longer a lot more would have come out."
On the Carnaby Street posing task, in which both Risikat and Roxy were voted to have performed better than her despite storming off, Kellie stated: "You just have to not care what people think.
"I got the least amount of votes and two of the other girls weren't even doing the thing - how does [Risikat] think I felt? You just genuinely have to shrug it off and if you care what everyone is going to say to you then you'll end up in a bloody mental home."
Asked whether she was thinking at the time about how the pair's tantrums could benefit her, Kellie continued: "I didn't look at the other girls as my competition. We're all just so different.
"All the time I was just always looking at myself and my work and how I could do better as opposed to, 'Ha ha she didn't do well on that'.
"I can see why Risikat was upset by it, she kind of felt like she was being objectified. She is a strong female and I do see where she was coming from but I personally thought it was just for the craic."
Even though more temperamental girls have remained in the show over herself, Kellie expressed the belief that she doesn't have to stop being nice to make it as a model.
"I don't think you have to be stroppy to be a good model or be successful," she said. "I think the competition has taught me that I have to be confident and I have learned so much about myself and my feelings towards people.
"Even if I never model again I just feel like I've grown so much as a person and it has definitely given me that confidence and taught me to work on that confidence."
Britain & Ireland's Next Top Model continues Mondays at 9pm on Sky Living.