"Young Enough" is about a 23 year old recent college grad who at first thought the 8-5pm routine weekdays, climbing the corporate ladder, and living lavish weekends were what he wanted. After 8 months of doing the same thing over and over, he finally shifts paths and chases what he really wants.
"Are we still ... ? " is him questioning himself of the path he's taken. Since changing directions, he's not able to see his friends that often, most weekends are sacrificed working, and of course FOMO (the fear of missing out) on his youth.
"You're all I need" isn't necessarily a person or physical being in the present but rather his future self, his future family, and his future lifestyle that he envisions.