I was subscribed to french teen magazines when I was younger, partially to practice my french (bilingual family), partially because they were gender neutral, (and also genuinely interesting to young people and not partronising- I read them until I was in my first year of university).
There was a "girls talk" and "boys talk" page that was like an agony aunt type thing about puberty, relationship problems, drugs etc. The other sections of the magazine where all about neutral topics like musics, films, clothes, technology, current affairs, study tips. I loved them, and to my knowledge they are still equally good (occasionally flick through a copy of the 15+ aged one in the library
)
I definitely remember looking at kids magazines on the shelf in WHSmith and noticing that a) most of them were strongly gendered and b) Very few that 14-20 year olds would be genuinly interested unless it was for a specific age group- no general interest ones.
Closest one I've found in the UK was "Flipside" although that leans a bit more male (video games, technology, films...)