Im not 100%, but I think a scan can show how thick the lining is and then determine where you are in your cycle. I could be wrong though.
I know my preg last month was nothing to go by, but I spotted for about 4 days when I got my BFP. And, lots of people in here told me that was normal.

i feel your stress, but try not to think about it too much. Let nature take its course (I do know how hard that is. )

Temping tomorrow sounds like a good plan.