Book in 90s/early 00s with time travel/world shifting with two tier society

Question

I'm trying to remember a name of a book or the author that I read in the late 90s/early 00s. I read a lot by the same author, and she seemed to specialise in teen scifi/fantasy with romance. A lot of her books had a feature where you could read them in either direction and you got the story from someone else's perspective. So basically two books in one, one starting from the front, the other from the back.

Specific elements I remember from one of them are the girl either travelling forward in time or side stepping worlds, (pretty sure it was the former) where she meets a boy (or he takes her through, again, not clear), he takes into some kind of body morphing booth so she can look like the people there. The future has a two tier society where the rich live really high in the air, and are slim and beautiful, the buildings were build on massive stilts and eventually there were roads and stuff built up there too. The down below are less genetically blessed and live in poverty on the old level roads.

I'm pretty sure it's not any of the Ace doubles or Tor back to backs because both sides were by the same author about the same events. I think the covers were green and yellow with a boy's face on one side and a girl's face on the other.

Answer 1

This sounds like it may be Terminal Chic by Chloë Rayban. It's available as an eBook on Amazon

These days falling in love can happen at the touch of a button and when it happens to Justine, it happens in a BIG WAY! A few e-mails and she's head over Gucci heels in love with Los, but there's just one He's from the year 3001. Justine is going to have to time travel to be with the one she loves but will she adjust to the technically advance society Los lives in And will Los be able to adjust to Justine's way of seeing things All's fair in love and cyberspace. A fun and stimulating look at life in the future. Will future scientists really prove that love is just a hormone imbalance curable with medication What will be the role of men as cloning and genetics advance And as technology and medicine improve - where will we put all our great-great-great-great-great grandparents

Edit: she previously met Los, who lives in the year 3001. He arranges for her to timetravel to his time. Once she arrives, she is put into a suit where she can make changes to her body - she gets a smaller waist and bigger breasts. She meets up with Los and navigates a city in the clouds - the Upside. She stays at his house and shenanigans ensue. At a party, she is mistaken for a Downsider, and taken to a place where she is stripped from her suit and dewired, then thrown into the Downside. The Downside is the old Earth. She finds her way to her old house, then the science museum.

The only thing that doesn't match the description is there being two POVs. The Justine Duval series is only from Justine's POV.