This is Jess. She IS a waitress. She is having an existential crisis, and the customers are NOT helping.

'A (adjective/s) waitress having an existential crisis ...'

Also, I find 'existential crisis' a bit vague. Instead, how about telling us what triggers her crisis.

This doesn't really tell us what happens in the story. As was already asked: How did this crisis occur? How does it affect her? What does she do about it? Since I don't know any of this, I'll create an example of what it could be all about -- then you can add actual pertinent details to the same form.

A career waitress questions her very existence when normally pleasant customers start treating her with relative indifference.

Still not much to go on, but at least I have an idea of what's happening, and there's some intrigue regarding the mystery of the change in behavior.

Or:

A disturbed waitress must solve her existential crisis when her regular customers start disappearing and no one else seems to notice.

Again, I have no idea what the story is actually about, so this is just me presenting random strange conflicts. But we definitely need to know more about what's going on in the story, and how the main character fits into all of it.

Okay I actually laughed at this one. In a good Way!!! Sorry not in a bad way. I thought it was pretty funny. What I can suggest though, is that instead of just putting the name, write an adjective explaining her (as said above). This will help everybody involved to invest more thought into the character. Also describe your customers, albeit not one at a time. As a whole, would you say your customers are cranky? Big headed? Arrogant? Describe your customers as a whole in order for us to get a sense of what brought on Jess's existential crisis, and how it affects her. Hope this helps!