54 days late!! Please help

Hello! I'm currently 54 days late and am confused. I had a doctor appointment scheduled on Jan 15th but it was pushed forward. The first day of my lmp was Nov 26-Dec 3. My cycles are usually 28 days so I was due Dec 24. Hubby and I bd at the right time during this cycle. I took an hpt on Dec 25 and Dec 28 and both were -. I currently have no symptoms that I've noticed other than very light spotting on Jan 7-8. Please don't say wait to see the doctor because I just want some peace of mind until the appointment thank you. Can anyone suggest what could be wrong? 
UPDATE: healthy weight, no more stress than normal, I don't have any special medical conditions, haven't changed my routine or had any major life events recently and I am an averagely active 20 year old :) I hope that helped!