Is it mind over matter?

I had March 7th unprotected but fiancee used pull out method. On the 23rd I had my period it only lasted 2-3 days (which is so not normal for me, I'm a 7-10 day girl plus it's usually heavy on the second day, in this time it wasn't plus I was 4 days late.) a few days later I had brownish discharge almost like spotting. Since then, I have been nauseous, my have been hurting for two weeks, and I am so tired I need at least two naps plus my nightly sleep a day. I've taken hpts and got a blood test on the 6th but they came back negative. I wouldn't think seconds on that except my first pregnancy blood tests didnt show up until 6-7 weeks past fert/implantation or whatever. Could it be that I am pregnant or is my mind playing tricks on me?