2021

As a junior in 2021, Whittaker ran under 2:02 in the 800 m six-times and competed at the US Olympic trials, reaching the semi-final. At the Brooks PR Invitational in July, she won the mile in a time of 4:38.65, the fastest time of any high schooler in 2021.^[2]

2022

In May 2022, Whittaker became only the second high schooler (behind Mary Cain), to break the 2 minute barrier in the 800 m, by clocking a time of 1:59.80 to beat a field of professionals at Icahn Stadium in New York City. The following month, she broke Cain's high school national record of 1:59.51, running a time of 1:59.04 to win the USA U20 Championships at Hayward Field. In August, Whittaker competed at the World U20 Championships in Cali, Colombia. There she won a bronze medal in 2:00.18, only behind fellow Stanford commit Roisin Willis and Swiss athlete Audrey Werro, who both ran under the previous championships record.^[3]

2023

In fall 2022, Whittaker enrolled at Stanford University, joining the Stanford Cardinal track and field and cross country teams. At the 2023 NCAA Championships, Whittaker contested the individual 800 m as well as the 4 × 400 m relay and the distance medley relay. In the 800 m, she placed second, going 1–2 with fellow Stanford freshman Roisin Willis in a time of 2:00.05. She also anchored the Stanford DMR to a first-place finish and ran the third leg on the twelfth place Cardinal 4 × 400 m relay team.^[4][5][6]

During the 2023 outdoor season, Whittaker won the Pac-12 800 m title, but chose to contest the 1500 m at the NCAA West Regional Qualifier. However, she failed qualify for the NCAA Championship after placing eighth in her heat.

2024

Choosing to contest the 800 m at the 2024 NCAA Indoor Championships, she won her first NCAA individual title in an indoor personal best of 1:59.53, also breaking the meet record.^[7]