From Gortin in County Tyrone, Flanagan attended Sacred Heart College, Omagh before earning a scholarship at Adams State University in Colorado. Whilst at Adams State she set a new NCAA Division II record in the 1500 metres, and won the 2021 NCAA Division II Outdoor Track &amp; Field Championship in the 3000 metres steeplechase, as well as finishing runner up in the 5,000 metres in 2021 and the 6,000 metres cross country race in 2019. She has run for the Omagh Harriers, and the Carmern Runners Athletics Club. Her twin sister Roisin is also a distance runner and in scholarship at Adams State University and is the Northern Ireland 5000 metres record holder. Both twins were part of the Irish team which won a women's under-23 team silver medal at the 2019 European Cross Country Championships in Lisbon.