As mentioned in a previous post, I am using a caterer (for a cocktail party) for the first time. I've selected a woman who catered a family lunch - her food is very good. We've been in touch via email and have swapped some ideas, food-wise. I have no contract yet.
Talk to the person that used her before. Find out if they had the same run-around and if they worried about the service. How did this person find the caterer? Have other family members used her before?
Ask the caterer for a list of references.
Sometimes great "artists" are scatterbrained about the business end, but pull off a wonderful service in the nth hour (while you stew and worry.

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Since she's given you 3 menus/prices I think you should e-mail her (tomorrow) and let her know that you have a few questions about the menu, the contract, etc.
Caterer:
I've received your menus/price lists and they look great. I would like to discuss a few finer points concerning my party, your services and a contract*.
Please let me know when you are available so that we can set up an appointment where we can discuss the event in further detail, either in person or via phone call. I am available (or not available) at these times/dates.
Your prompt attention to this matter would be greatly appreciated.
Queen
See how/when she responds.
No need to give her an "out" (unless that's what you want to do) because you haven't signed a contract yet (maybe that's why she's a bit lackadaisical?) At this point, to her, all you've been doing is fact-finding.
If she doesn't respond in a timely manner (that fits
your schedule . . . after all you are the customer) then there is no need for further contact with her at all except the polite "Thank you, but I've hired a different service."
In the mean time, start looking for alternatives PDQ. Just in case.
*Contract issues: When does she need a final headcount? Deposit? Cancellation clause? How does she handle specialty items (allergies, vegan, etc.) Are her servers bonded? How many servers? Clean-up?