How about this one?
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Dear Doc,

I know I wasn't the easiest patient when we worked together. However, after giving more thought to the idea of asking you to be my doctor...I realized I need to give more consideration to your thoughts and feelings.

In order for me to better consider your thoughts and feelings I would like to ask you a few questions. Would you ever consider being my doctor? If so, what would it take for you to be my doctor again? Please be aware at this point I know I have more work to do before asking you to be my doctor. The reason for asking you these questions is so I can get a better idea of where you stand.

Understand that I realize that an answer to these questions in NO way initiates the patient doctor relationship. This would be strictly informational only. If you choose not to answer this I will assume that would mean you are not at all interested in being my doctor ever again. At that point, I will forever leave you alone no matter how difficult that may be.

I look forward to hearing from you. However, I would totally understand if I don't hear from you given our difficulties in the past.

Thanks,
Melissa
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I hope this one sounds better.