I can't help feeling old

I'm turning eighteen in November, and I feel so old.

I don't want to grow up, because that means that I have to decide what I want to do with my life. And I don't have a clue. I know I should have some idea by now, but I don't know.
It's so hard. All my friends have their plans, and we're all moving away from each other. I don't want that to happen, but it's not like I can avoid it either.

And when I hear about people I know, people that are the same age as me, or even younger than me, getting engaged. I mean they're like getting married soon.
Do people usually get engaged when they're 17/18?

Really I don't care what they're doing with their lives, but they're making me feel old. For someone that doesn't really want to grow up, it's a hit in the groin.

I've been avoiding reality and the outside world this summer. Just because they make me think about things that I don't want to think about, and I'm feeling to young to even consider.

I don't want to grow up. I don't want to grow up. I DON'T WANT TO GROW UP!

I'm scared.