Trashileva had been part of the Bulgarian national team competing internationally since 2012,[1][2] including the 2012 junior European Championships.

[5][6][7] In 2015 Trashileva had a fallout with Angelova, causing her expulsion from the national team, the motivation given was "a systematic violation of discipline, non-compliance with the instructions of the coaches and the creation of an unfavorable atmosphere, which interferes with the normal course of the training process".

[8] However a year later, in July 2016, Zhenina was invited to take part in the national group selection for the 2017-2020 Olympic cycle.

[19] In June she was part of the group for the European Championship in Tel Aviv, she won gold in the senior team category along with Vaya Draganova, Sofia Ivanova, Kamelia Petrova, Rachel Stoyanov, Margarita Vasileva and the individuals Boryana Kaleyn and Stiliana Nikolova.

The 2023 season started in Marbella, where she won the All-Around with the Bulgarian team, as well as the gold medals in the finals with 5 hoops and with 2 balls and 3 ribbons.