I am attempting to write a relatively complex SciFi military novel following 3 primary characters. A male and female protagonist, and a male antagonist. So far none of those characters are aware of each other, but their individual paths overlap to create the whole story. Each chapter focuses on an individual character, often referencing events from other character's chapters that the primary of that chapter does not recognize as directly important. In a way it is more like 3 simultaneous stories that intertwine. The story is written in past tense, third-person with frequent present tense, first-person asides to act like an internal monologue by the main characters (I hope that makes sense).
I am roughly a quarter to a third of the way through the story and I am really struggling to write the female character well, likely because I am male myself. I am entirely expecting to completely rewrite some of her chapters if necessary. Here is a quick overview of the 3 characters. To simplify explanations a replaced the names of organizations with their closest modern equivalent as "Space _____".
- Male Antagonist: Late 20s/early 30s (age undetermined). His mother was illegally immigrating from one planet to another and died mid-journey in childbirth. The smuggler kept him as his own son which eventually led to his membership in "Space Illuminati" intent on destroying the current unified government, which he blames for the hardships of his life. He has undergone extensive surgeries (to the point of being a different person in nearly every way except retained memories) for the purpose of infiltrating military intelligence. Infiltration failed almost immediately due to unforeseen circumstances, but during his escape he nearly destroyed the "Space Pentagon". This has propelled him to the upper echelon of the organization, but many feel he is not worthy of his authority. He is highly intelligent despite only receiving formal education in his adulthood, but suffers from a stutter and inner aggression issues that sometimes border on psychopathic.
- Male Protagonist: 27 years old. Highly skilled military officer who is regularly promoted and put in various positions of authority, despite lacking very much self-motivation. Superiors confuse his perfectionism and controlling nature for discipline. He originally trained as a drone pilot at military academy until his father inadvertently caused the death of his pregnant fiance, which was then covered up. He continued in military service as a tactical officer for the simple purpose of staying away from his father. He was recently promoted to Executive Officer of a Destroyer and is nine years younger than the average for his rank.
- Female Protagonist: 22 years old. Engineering officer with a genius level IQ and temper issues. She prefers dealing with machines over people, and struggles to make genuine connections. She struggles with economic and racial prejudice against her as she is from a planet that enjoys numerous health benefits caused by the environment and is wealthier on average despite not being economically important. Her position is often looked at as a perk of her birth rather than her actual ability. In her last year at the military academy she was recruited by the "Space CIA" as a potential asset because the "Space Illuminati" is likely to try and recruit her because of family ties. Her motivations lie in uncovering why her late grandfather, a vice admiral in military intelligence, committed treason and aided the "Space Illuminati".
My main issue is that I feel like I should have enough to build a strong female character on par with the male characters, but when writing her I tend to describe the environment or give more backstory than actually describing what is happening and what she thinks. I have transitioned from originally intending her to be in her late teens, but it started to seem too much like a young adult novel, and I really didn't want her to turn into Catniss/Triss/Clary from those associated books.
From what I have written above, what should I focus on with the female character to help give her more depth and improve my writing?
Please let me know in the comments if you have any questions or want any more details. I am also totally willing to let you read some of the completed chapters if you think it might help.