help describing a haircut?

Asymmetrical bob is probably enough. Maybe in dialogue?

____________

I asked for an asymmetrical bob.
The hairdresser nodded. "Bangs, or no?"
"Yeah, but side swept, if that's okay."

________________________________________
Or I dunno. I think keep the details to a minimum unless it's crucial we know.

Unless it's got a role to play in the story, saying "a long, asymmetric bob" is enough.

Yup, you don't have to give to much of a description if it is not relevant to the story.
It can also depend on the type of story you are trying to tell, and if lots of description is expected.

You didn't say what your target audience was like. An olde timer like me might describe it as a "thima-a-bob haircut with one eye hidden, for no good reason." Us geezers understand crew cuts but peek-a-boo haircuts went out with Alan Ladd movies, War Bonds, Studebakers and Veronica Lake.

I had my hair cut like that a few years back and the hairdresser called it a graduated bob. (This is in the UK, in case that matters.)

"An asymmetrical bob with side bangs" if you want the complete style explained.

Rarely, you'll see it called a New York bob, but that's mostly inside the fashion industry. So, if your character doesn't work / think about the fashion industry too much, I would just go with asymmetrical

According to a colleague's stylist that's considered "a Rachel with attitude" . . . (I'll admit I have no idea what that means ).

I hate to overengineer things, but it really depends on the story you're telling, the narrator's relationship to the character being described, why the haircut matters, etc. There are so many ways to approach a physical description.

One of the great things about writing is that you learn how much you don't know in many areas. I'm not to good at describing hair cuts, but I do know I can google different types of haircuts and learn the basics pretty quickly. What you've written sounds good, but keep it simple. You want to point the reader in the right direction and let them decide for themselves with their own imaginations what it looks like. That's the beauty of books. Unlike movies where everything is done for them, readers get to decide a lot of things.