Themann was born in Shepparton, Victoria, Australia and was raised in the nearby town of Mooroopna.
In 2016 she was a member of the Newbridge team that won the Loddon Valley Football Netball League premiership.
[3][11] Between 2006 and 2008, while still attending Caulfield Grammar School, Themann played for Melbourne Phoenix in the Commonwealth Bank Trophy.
[7][12] In 2010 Themann began play for Melbourne University Lightning in the Victorian Netball League.
[8][9][13] In 2016, together with Shannon Eagland and Elle Bennetts, she was a member of the Lightning team that won the VNL Championship.
She attracted the attention of several senior teams following her performances for Scotland at the 2015 Netball World Cup.
However, having declared for Scotland, she was reclassified as an import player and in 2015 a deal to sign for Queensland Firebirds collapsed as a result.
[2] She helped Scotland qualify for the 2019 Netball World Cup but missed the tournament itself because of pregnancy.