What Causes Delayed Period Inspite Of Being On Birth Control Pills?

Hi i take azurette BC pills and this month I missed a hormone pill two different times and took them both the following day when I remembered. I usually get my period on the third week of the pack religiously but I am now 4 days late. I took a pregnancy test on the first day of it being late and the test said negative but I m having some symptoms like sore breast that could be a symptom of my period being late or possibly pregnancy symptoms. Idk what to do, I need to know if there s a chance I m pregnant. Please help!!!!