Writing "Young"

I have been writing for an online magazine for about three weeks now.  I was concerned at first about the age of their readership, which is about 16 to 25.  I'm going to be 50 next April!  I am the mother of a 9 year old so parenting and kids' stuff are easy, but it's not all I want to write about.  How on earth do I write younger than my age? 

Firstly, it's been almost 25 years since I was 25!  When I was 16, I was so incredibly shy that I never spoke to anyone so how would I know what other 16 year old girls were into?  Some of the topics I've seen on the site are about choosing the best shade of lipstick.  Lipstick?  Honestly, I'm lucky to find time to put on makeup at all.  Great vintage hairstyles is another article I came across.  I'm happy to have hair still!  I also spotted the article on Inspirational rap songs to listen to when you're down.  Is there such a thing, really? 

Coming upon the midway point of my life (hopefully), all I know  firsthand to write about besides my sweet boy, is how not to pee when you sneeze or cough, when NOT to roll your eyes at a teenager you see making an idiot of themselves and hoping your kid never does the same thing, and what Spanx will do to you if you don't get those suckers pulled up all the way. 

Any suggestions for writing for the younger generation of women?