Hi Jenny,
I just wanted to say, there's so much stuff going on down there with the uterus, the ovaries and the bowels, just to name a few, that it's hard to speculate exactly what you might be feeling. I know bowel obstructions are common with CF and cause sharp shooting pain and then it subsides (sometimes, for me anyway) or it could be a kinked intestine causing pain. It sucks to have to say, you should wait and see what the officials have to say about it, cause I wish I had a cause for you. Based on what you describe it could be endo related, it could be bowel related, it could be ovulation related....the list goes on.
Keep us posted on the RE appointment. I wish I had better advice.
Tara