If I had not met the red-haired boy whose father (1)
This line might not seem like it has much to do with identity, but it's the beginning of a very long sequence of events that helped shape who our speaker is. It all begins with a red-haired boy.
and if I had written anything else at the topof the examination form where it said college (10-11)
The choices the speaker made a long time ago, in his youth, affect who he is now, even if they didn't seem like a big deal at the time. So, straighten up and fly straight, all you young Shmoopers out there!
I would not have found myself on an iron cot (19)
This is the point in the poem where the speaker starts to think about himself (finally). He's been chatting about all these other people, and now he's taking the opportunity to consider exactly who all of this makes him.