Implantation Bleeding vs. Period???

I am totally new a this TTC business. I have been using glow since my last period June26-29. My fertile days were roughly the 7-13 of July of which we BD'd 4/5 days. I took 4 HPTs about 6 dsys after (I warned you all I'm new at this!) and I also had a serum hcg done which Was negative last Wednesday. Today I have light spitting and mild period symptoms a week early? Implantation bleeding? Did I test too soon?