help

[b] I have a question.I went to the doctor yesterday and took a test and it came back negative. It was a urine but I requested a blood test and she siad I did not need it. I recently had sex two days before Could the test be wrong and do I need to wait and see? i been having the symptoms but thhe test is negative and I believe I am. They say ablood test can give you results in a day or two as well as a lab test. if you hhad unprotected sex. I am just curious and would like to know