19 days late with period and negative test!

Okay, I need help. My last period was March 7th and I am usually regular and on time. I have very mild pregnancy symptoms but all test including blood test for pregnancy came back negative. I've been late for 19 days now and still nothing, has anyone had this issue before? I've spoken to my doctor and he feels like I'm having pregnancy symptoms as well and basically everything else is ruled out so I have no idea what it could be.