Missed Period, Negative Pregnancy Test... uhh what?

So I’ve missed my period by 3 weeks now and I had unprotected sex twice, the week after ovulation. I had a brown goe-y discharge 1 week after that. And I was supposed to get my period the 11th of June but haven’t received it. I took a pregnancy test last week and it was negative. Im having cramping and I feel like I have my period but I don’t. I’m not sure if it’s because my body hasn’t produced to much hcG to be detected by a home pregnancy test cause that happens sometimes or there could be another issue going on? Any thoughts?