Missed Period, Negative Hpt. Ultrasound Shows Lots Of Follicles On Ovary. Pregnancy Or Anything Else?

Hi, I recently had intercourse on 11/15/12 and was due for my period 11/18/12 its now 11/30/12 and still havent gotten period. It had previously been over a year since i was last with anyone and im not on birth control and we didnt use a condom, he pulled out, it only happened that once. So ive been stressing out if im pg , i took a hpt and it was neg. i had my friend do an ultrasound on me last night trans abdominal and she said i had lots of follicules my ovaries are around 4.5cm x 3.7cm and largest follicule she saw was 1.7cm x 1.2, but there were many more. So my question is can i be pregnant or is there something else wrong?