Blood test shows negative on the 2nd day of delayed period?it's been 8 days of my delayed period?

i know that my ovulation is around dec 14 or 15 and i supposed to get my period bet dec 26-30 but it didn't come out.i took hpt in the morning of jan 1 and it showed negative & i had blood test in the evening & got the result on thursday evening and it showed negative.. on that same day, thursday morning, i took clear blue and it showed negative but till now, i haven't have my period.my ob gyn already gave me a medicine that would help "release" my period but still in a deep thought???could it be too early for me to take the blood test and hpt that's why it shows negative or i'll just believe in my ob gyn.i don't have any symptoms whatsoever..just on thought...also, is it ok bec. i ate before i had blood test.i had my BT at around 7:30pm and i had my last meal and drink (softdrinks that is) at around 3:30...will it affect?this is the first time i didn't have my period..is it because im thinking too much..if i'm preggy i would have been on my 5th week bec my last period was nov.29..