4 days late?

I started bc pills Sept. 10th when I was on my period ended the 15th, then I started bleeding from the 23rd and stopped the 30th and I had unprotected sex 4 times last month before and after period, I don't take my bc pills in the same time frame, I made a doc appointment and she said it was normal, I also took a pregnancy test a week ago said negative but they were cheap, I missed a few pills would that be the case?