6000 crew aircraft carrier? What balance of genders, I wonder?
From a very casual google search, this is the breakdown of the US military as a whole -
Males account for 84.4% and Females account for 15.6% of the total. The Racial/Ethnic distribution of the Army is as follows – White, Not Hispanic: 54%, Black, Not Hispanic: 20.2%, Hispanic: 17.2%, Asian or Pacific Islander: 6.9%, American Indian or Alaskan Native: 0.9%, and Unknown/Other: 0.8%.
10-20% female population could be an issue although it can also reduce the risk of overpopulation as they settle into an equilibrium.
I think part of the issue would be that they're career minded women so not necessarily keen to just be breeding factories. They'd also, ideally, be having multiple kids with multiple partners to increase genetic diversity.
However in the comic it seems like a lot of the first generation after Y0 waited until older to have children. Juha was born in 38, Ensi would've been 37/38 -
http://sssscomic.com/comic2.php?page=108And if you do the math on Mia Väserström, she had Torbjörn in her 50s/60s (she was alive pre Y0 and Torbjörn was 38 in Y90). Veeti as well - Taru was born about Y49, and Veeti was alive in Y0.
Honestly i think Minna just didn't consider the ages and just didn't want too big a family tree - but I do think the trend of having kids later right after an apocalypse is reasonable.