Hi, I Have Taken 2 Home Pregnancy Tests. One On

Hi,
I have taken 2 home pregnancy tests. One on Friday had a VERY faint result line. I called my doctor's office and they recommended I go in for a urine test. Their test came back negative. I took another home pregnancy test on Sunday and the result line was a bit darker than the late, but still faint. I was to start my period yesterday, and still haven't. I just need to know if it's safe to assume I'm pregnant even though my doctor's test said negative. Any advice will be much appreciated.

Thank you.