Could I be pregnant?

I have been having unprotected sex with my fiancé for about a year now and I am now 3 weeks late for my period...! I think it's very possible that I am pregnant. I have been moody and emotional, I've had muscle pains, clear watery discharge, and I feel nauseated throughout the day. But get this, NEGATIVE pregnancy tests! Every pee test has come out negative. But I'm still showing symptoms. I know my hormone levels could be low which is why I went to urgent care and they took a urine sample that also came out negative... so question is, could I still be pregnant? Or why else would this be happening? I have had regular periods for 2 years since being off birth control. Can someone please help?