I don't write for young adults. I'm a little out of the loop, I believe. My oldest grand child is 16 years old, and an avid reader (PTL!) but I'm not into the lingo, the pop culture, the techo-activities. I remember well MY angst as a teenager. Angst over boys and dates and parents, pimples and clicks and ugly PE uniforms.
But I think even the level of angst, or maybe the way contemporary young people deal with it, makes my generation far removed from middle school and high school students of today. God has neither gifted me, nor called me to write for 21st Century young adults.
However, I know many writers who do a fabulous job of speaking to young adults through literature. So, I offer this link to you.
NPR's Top 100 Teen Books in 2012. This list bears neither my personal recommendation nor warning. It's simply for your information.
But I do recommend this: if you want to write in a specific genre, or to a specific audience - read what they read.
And the choir all said, "Amen!"