Also agree with the above.

Do not let any seller put you off again and again. That is not the way straightforward people do business.

You are doing all the work to keep things "nice", by giving her the benefit of the doubt, again and again. You can be polite with a professional tone and still set time limits and take next steps. If you feel that your logical next steps don't feel cordial, even if your tone is business-like, just realize that you aren't the one breaking the cordial relationship. The seller is doing that by putting you off. Especially for a significant sum.

Don't worry if she will feel offended by your necessary next steps. She's already offended you. However she responds, this is likely not her first time in this situation. She's more used to it than you are.

Good luck!