Hi Angelica,
It does depend on your cycle length, but 'generally' speaking (well from what I have read), you get your period approximately 14 days after you ovulate. So going by your ovulation date, you would be due on roughly on Sunday. Would that fit in with your usual cycle?
As for your back pain, the big problem with pregnancy symptoms is that they are really similar to PMS symptoms. That's what we all moan about!!

It is really easy to 'forget' your usual symptoms in the 2ww - last month, I was convinced that my boobs were more sore than usual, that I felt really tired etc etc!! Unfortunately, it was just my AF approaching. Anything unusual for your cycle should be noted.
However, just because you are getting your usual PMS symptoms does not mean you are not pregnant - you still could be, just wait to see if your AF turns up.
Good luck,
I hope you get your BFP!
