I've been looking for a book I read probably in the late 80's to very early 90s (pre 1994). My recollection is that the main character was a girl who lived in a dystopian future where kids were bioengineered & society lives in tunnels/underground/dome. Most were the same but she was created different - much taller, smarter & with boobs (a detail that stuck out for some reason). I remember reading that she towered over the men & filled the tunnels. As part of coming of age & finding job process, she takes a test which reveals something (I believe the AI told her something the leaders didn't want known maybe?) & she ends up either running or being kicked out. She's joined by a boy (of course). I remember they tumble down a hill & land on the remains of a highway. The middle is very hazy. I think that there must have been good descriptions of how things degraded because I feel this book was what spurred me to look at things and imagine what they'd be like in 100 years without human intervention.
They end up discovering a space ship and are able to activate it. I believe the last pages are about them going into space but I seem to remember wondering why they wouldn't go to other places to tell them the outside is okay. I've always thought it seemed perfectly set up for a sequel.
I searched the previous questions asked about dystopian books and none seemed to be the one I'm thinking of.
Apologies for not remembering more. I believe I was mid teens and it's been a few years...
Any suggestions? Thank you very much!