"Hyperventilating, breathing shallow,
others stare in curiosity, confused."
`Great description, we can already tell that your fear is being in a small place, your phobia is claustrophobia..youve described what its like very well to be inside someone with that fear. It's soo common and many people have it.

"Such a confined place, so small.
Dings remind of each passing floor."
`Oh wow, I liked how you actually put us in a situation in which youd be claustrophobic.. an elevator is a great example.. its always so crammed and you feel as though you cant breathe because all of the people around you.. I know the feeling being in such as small confined place such as an elevator like youve said here.

"Claustrophobic beyond need,
eyes keep staring down in chagrin."
`I liked the word choice here.. chagrin, a word I'm not normally familar with hearing.. good job.

"Doors open quickly, people rushing,
my breathy sigh finally released. "
`I know this feeling well myself, that sense of relief that everyone is leaving so therefore you feel like you arent claustrophobic anymore. Youve painted the scene of being in an elevator and suffering from this phobia to the T, youve done well dear.

5/5.