I Had Unprotected Sex On March 25th 2016. Today Is

I had unprotected sex on March 25th 2016. Today is March 31st 2016 & I have taken about 5 Urine test & they all come out negative. I Have not had my period this month and I'm 10 days late, my boobs feel tender (but I doubt that's something), & today I also had brown discharge with blood in it and it was wet, so I don't know what this mean. I was wondering if Blood Test are more accurate? Do you think I'm pregnant? Or is my period just really late? When do you recommend I take a test?