Inconsistent Pregnancy Test Results, Microscopic Blood Particles In Urine.

I have taken 3 pregnancy tests in the am and all have came out positive my period was due on the 4/20/2012 and has not came went to health dept to have a test done and the nurse said that it was negative but i went in the afternoon and she also says that there is microscopic blood particles in my urine she was not very helpful in answering my questions so now i m even more confused and a bit worried is there any suggestions that would help me?