I DNF at 57%
It was like the author edited out chapters and then forgot readers no longer had that information. Because they'd reference something that never happened.
But I went with it until this tidbit gets dropped...
“Well, another side effect of the cascade bomb event was that it triggered a genetic mutation, so certain parts of our brains, more notably the parts for intellect, mature something almost twice as fast as they used to. So, in reality, physically we may look seventeen, but our brains are really—” “Thirty-four? Ew.” Laney wrinkled her nose.

Ok so first off, I don't think brains work as just described. Just because they can grow into their brains faster doesn't mean they have had the time to learn all the things they'd need to learn everything to become top scientists AND super soldiers. Just because you have the intellectual capability to understand something doesn't make you magically know everything, so they will wouldn't be able to advance that quickly. Plus intellect and maturity aren't the same things.
So if they've been dating since they were in 11 year old bodies that had matured to an age 22 brain, wouldn't that mean to them, New Laney is basically an 8 year old in their world? It's really weird any way you look at it.