Had unprotected sex. Had brown spotting. Pregnancy tests negative. Experiencing pregnancy symptoms. False negative?

Hi I am really confused, I think I may be pregnant but all the HPT say negative. My last period was Dec. 12 and was pretty short. I had unprotected sex on Dec. 18, 19,28 and 29th. Beginning on Jan 7 I started to have some brown spotting, it was irregular and came and went for anout 2 days. Then it turned to a very light red, not at all heavy enough for a period, that lasted a day or two and then I got the brown spotting again but it was thicker almost with brown clots. That all stopped about a week ago and I have not had anything since. I have taken 7 HPT that all say negative but each day I am noticing more symptoms of pregnancy. Extreme Fatigue , about a week and a half of headaches , frequent urination , moddiness/emotional, abdominal bloating for about a week straight that has not gone down, unusually sore back and mild nausea (usually while driving). These symptoms are getting to the point where they are effecting my day to day routine so I am getting worried. Is it possible to have a false negative this late or is it likely something else? Thank you!!