Please help so frustrated

[awesomeme]

My last period was may 28th 2013 and it lasted 3 days i have yet to have another period and me and my boyfriend have had unprotected sex on what i think may have been one of my ovulation days.have taken tons of dollar store tests and even went in and got a blood test but it was negative. i have nausea, headaches a lot lately, very tired, grumpy, no period, cramps, and i have milky white discharge. My mother got negative blood and urine test for her first kid until she was 4 months and my older sister had negative blood and urine test until she was 3 moths with her second child. could this mean i am pregnant but its not showing like my mother and sisters. Please any advise will help me... im going crazy nt knowing ... thank you