Missed period

Hey guys, so i was wondering if this has happened to anyone else. Iv missed my period and am now 12 days late. I’m testing negative and have no pregnancy symptoms. My husband and i are TTC my period has always come around the same time even after I had my first son and I got my period back three months later and it’s been consistent ever since , I’ve never missed in my life and I’m not really sure why I missed now and still testing negative has anyone ever been this late and tested positive later I have a doctors appointment on Wednesday