Yes, that's correct. "Not in the right place" here means she wasn't emotionally or mentally ready or in the mood to celebrate her birthday. She likely felt uncomfortable or upset about turning 40 and didn't feel like having a party.

Hi Cyanstar. I don´t think she is referring to physically being in the wrong place but rather that she is in the wrong place mentally and emotionally. When someone is not in the right place mentally and emotionally it means she is unsure or something is wrong. It could be that she is upset about celebrating her birthday or she is upset about something else and therefore didn´t feel up to planning a celebration. I hope this helps.