Lastra began his rugby career with the Old Mackayans, he made his senior debut for the club in 2014.[1][2]
Lastra made his international debut for Chile against Brazil in 2017.[3] He played for Italian club Valsugana Rugby Padova in 2018, before his brief stint in Verona the following year.[1][3]
He returned to Chile to complete his studies after his stint with Verona, he later obtained a degree in Civil and Industrial Engineering.[1][4]
Lastra joined Selknam in the Super Rugby Americas competition in 2022.[1] Later that year, he started in Chile's history-making victory over the United States in the American qualifiers for the 2023 World Cup.[3][5]
He was named in Chile's squad to the 2023 Rugby World Cup in France.[6][7] He featured in the match against England.[3] Following the World Cup, he signed with Italian club, Rugby Rovigo Delta, for the 2023–2024 season.[3][8]
Lastra later joined another Italian club, Colorno in 2024.[1][8] In October 2025, he signed with Union Sportive Bressane, a club in France's third division, Nationale.[9]