Courtney made big improvements to her 800 m and 1500 m bests in 2013 and won the latter event at the BUCS Championships indoor and out that year. In the 2014 indoor season she won the Welsh indoor title and placed third at the 2014 British Indoor Athletics Championships. The 2015 season saw her drop her 800 m and 1500 m bests to 2:05.48 and 4:09.74 minutes and she made her international debut at the 2015 European Athletics U23 Championships, placing tenth in the 1500 m. Though she placed seventh nationally at the 2016 British Athletics Championships, she ran a best of 4:07.55 minutes and gained selection for the 2016 European Athletics Championships, competing in the first round only. She teamed up with Cameron Boyek, Sarah McDonald, and Tom Marshall to take a gold medal in the inaugural mixed relay event at the 2017 European Cross Country Championships.