Missed period last month, barely spotting this month, negative preg tests

Savannah
The start date of my last period was June 29, 2016. My period is like clockwork and usually medium to heavy (I track it), so missing it during July was a huge red flag (no pun intended), especially since I have never missed or been late. I have taken HPT's and all have been negative, and the blood test from my doctors office also came back as negative. Fast forward to now—I have had two days of very light spotting, which is very unusual for me, and today is back to a normal white discharge. I've been having periodic pregnancy symptoms since the beginning of August, but can't tell if they are legit or just in my head. HPT's are still reading negative. Has anyone had this or something similar happen before? Have you still been pregnant after negative tests? Anyone have any ideas of what this could be?