When I was a teenager, I remember spending several years primarily preoccupied with terror at the idea that I wasn't being myself, or, more accurately, that there wasn't a 'self' in there to be. I realized the more I thought about it that the things I liked and cared about -- anime, video games, English over math and science, the importance of art -- were all things I had picked up from my friends, that I'd never come to on my own.
I don't remember having thought that it was likely my friends had all picked up their interests from their peers. I thought I was the only one who was basically not anyone, just a weird reflection of all the people around me.
Then I worried that not liking all those things would be just as inauthentic as liking them was, because the experience of enjoying them was a real experience, because I didn't (and don't) believe that emotional experiences can be fake.
This is what I'm afraid of when I'm at my most depressed, and it's always reassuring to hear of other people who thought that "Be yourself" was bull████ advice, too.