I completely understand about 18+ stuff. I sort of assumed that was the case by the way you progressed the story and how it toned down to a more natural scenes. And it's not like I'm against steamy stuff
Regarding tech and science. You have a very nice way to explain things and while reading some things I was actually wondering myself what parts of science I would have chosen and tried to explain. I am certain that any moderately complex math problem would have been way more complicated for me.