I'm a senior.

it hasn't hit me how little time I have left.
I can't imagine that after this year, I have to choose what to do with the rest of my life.
How do I determine how much I like something if I've never tried it?
I can't fathom that I have to try to meet new people after this, that I won't be surrounded by the same faces I've had for 13 years.
How am I a senior?
I feel like I'm still just starting middle school.
I'm a senior.
How?