Late?

So i went to my doctors for a check up to see how i was doing with healing from my d&c and she said i could start my bc pills the sunday after i start well she said i was supposed to start on the 9th or around the 9th, but i swear up and down and so does my bf she said the 9th. Welp here comes the 9th and nothing and then the 10 and still nothing so rn im about 5 days late? And ive taken a test on the 11th but got a negitive...what should i do?