13DPIUI, BFN but spotting?

Hi! So this is weird... I'm 13DPIUI (our 2nd; 1st ended in chemical) and took a test at 11DPIUI and again today - both BFN. i should have started AF today but haven't, and I've been spotting just a little brown discharge off and on since Monday. I've read about implantation spotting but I guess I just thought it was a little bit then over.

I've got an appt with my RE tomorrow morning for blood and I am HOPING it'll confirm BFP. No real AF symptoms, no pain, just... weirdness.

Anyone else have a similar experience? Anyone waiting for their BFP along with me?