Take her up on it! She obviously knows that although she's cut and styled it, you will need to work with it yourself to 'know' how if the cut really worked.
Get the layers added in, and then go back the next time you're ready for a haircut. She's making the effort to ensure you are a satisfied customer, and if she wasn't open to re-cutting, she wouldn't have offered. Take her at her word.
Me, I'm lazy, and so I'd likely live with something I wasn't 100% in love with, (because I just put it up in pigtails or barrettes anyway)...however, I love the woman who cuts my hair and she always asks "so, how did the last one work for you" and we go from there.