me too!! I'm the exact same way and I planned my entire IVF cycle very carefully to avoid the number 13. I did not want my retrieval on the day 13 of the cycle or the 13th of that month, and if it had landed on that day, I would have found a way to push it to the 14th. So, I completely understand and would never criticize anyone for being superstitious.
So, in answer to your question, I personally would not go to the Weds. appt. and just plan to see her next week. If you have to go on Weds. because you have some issue, take your DH with you. That's what I would do.
Hope this helps,