Not due to Friday but....?

I am due my monthly bliss on Friday 8th May, I ovulated on 24th April and my cycle is always 26/27 days, had unprotected on Monday 20th April...from about 4 days after, so from friday 24th April i have been feeling sick, really sore and twinging in belly...For last 3 days i have actually been being sick...I am soo tired and my blood pressure has dropped to 97/60...which it did in my first pregnancy which was 13 years ago...I have twinges like im gonna come on but with all these other symptoms im begining to get impatient and want to do a test, trouble is i got 10 negative tests with my daughter so could someone tell me a good ultra early pregnancy test that is likely to show me definate result seeing as not due on til Friday.