What are the chances that I took a test the day before I was supposed to start my period (also mid day too) and it was negative but I don’t start my period that next day… that I am actually pregnant?

Today is my start day so I will test again tomorrow but I’m anxious about it… this is our first time TTC as our first was not planned and I didn’t test until after I missed my period so I’m not sure what to expect here really