Early symptoms

Incredibly sore boobs, my areolas will swell then go down but I'm spotting, brown and pink, no red. Cramping. I'm not anymore tired than I normally am, I work nights, 12 hour shifts so I'm always tired.  Took a cheap test today BFN. AF due on 9/16. I know everyone is going to say implantation bleeding but only 20% of women get it. Could it just be spotting in general, anybody have spotting then get a BFP? Thanks. I'm trying so hard to wait as long as I can so I don't waste a good pregnancy test. Any comments or hopes would be great!