She grew up in Houston, Texas, and was identified as an exceptional talent early enough that her development within the sport was closely tracked before she reached college. At Texas she became the face of a program that was already nationally prominent and elevated it further, winning the USA Softball Collegiate Player of the Year award multiple times and earning a reputation as the pitcher opposing coaches spent the most time preparing for and the least time successfully solving. She joined Team USA and won gold at the 2004 Athens Olympics, then silver at the 2008 Beijing Games, the last Olympic softball competition before the sport's removal from the program. She retired in 2010 and returned to competitive softball in 2021, rejoining Team USA for the Tokyo Games at 37 and pitching in the Olympics a third time, 17 years after her first appearance. The return alone would be a career for most athletes. For Osterman it was a coda.

She married fellow athlete Joey Carrasco and has been open about the physical demands of a comeback undertaken at an age when most softball pitchers are long retired, speaking in interviews about the work required to rebuild arm strength and the decision-making process behind returning to elite competition. She has coached at the collegiate level and remained connected to the game in the years since Tokyo.