Definitely get a blood test!
I went to the dr last thursday for a suspected bladder infection, my period was due on sunday so the dr asked if I wanted to do a blood test since I was going to the lab anyway and of course I said yes
i got the results saturday, the day before my period was due, negative for infection and positive for pregnancy
but I really wanted to see the two lines on an hpt (seems to make it more real) so I took one sunday am, first morning urine...And it was negative!!
So definitely get a blood test. I'm going to try my other hpt tomorrow morning, just to see if it finally shows up, i'll let you know