BFN but no period?

My last period wasJuly 20-26, I had sex on the 10th. My period was lighter than usual, but it was also heavier at some points. 
​Since then, I've been nauseous all day for weeks, tired, extremely moody, I've had cramps above my pelvis and in my lower back. I've eaten a lot more than I've ever eaten in my life, and my jeans are starting to be really right fitting.  
​But when I took some tests one was a BFN and the other was an electronic one and just gave me a "?"  

Glow Resources

Let’s Glow

Glow is here for you on your path to pregnancy

Glow helps you navigate your fertility journey with smart tools, personalized insights, and guidance from medical experts who understand what matters most.

25+ million

Users

4.8 stars

200k+ app ratings

20+

Medical advisors