Is it possible to get pregnant one week before your period is due

Patient: Hi,I was taking norethisterone to help skip a period. I was due to start my period on the 5th of December 2013, however was taking the norethisterone so did not have the period as planned. From monday the 2nd of December until sunday the 8th of december i had unprotected sex. I understand that norethisterone is not a contraceptive also i understand that since it was four days before my expected period and four days during my expected period, it means i would not have been ovulating and would have been having sex in the ‘safe period’ of the month.I stopped taking norethisterone on sunday the 8th and had my withdrawal period on wednesday the the 11th. The period was extremely heavy with clots of blood on the first day…then on the second day…i just had a a light bleed and some brown clear discharge…and then the rest of the week was light. it lasted for five days. My period is not like that normally, but i assumed it was just because of the withdrawal bleed.for the rest of that week i had no appetite and had terrible cramps and felt nausea and had migraines. I assumed this was because of the withdrawal from the norethisterone. However this continued for three weeks on and off. I noticed the symptoms more at night. I feel nausea when i would like down. I felt dizzy sometimes when i stood up. I took a pregnancy test and it came up negative. I took this maybe four days ago. which is six days before my period is due. However i decided i should calcuate when i ovulate so that i dont have sex in that week to avoid pregnancy. I used an ovulation strip which gave a positive result. This was seven days ago….every day since then. the results have been positive. I assumed since i was ovulating that it meant i couldnt be pregnant but thought it was strange to ovulate for seven days. I went online to try and find reasons why this could be and many women were staying that they used ovulation kits as early pregnancy detectors and that most of theirs showed positive for some days. Now it is two days until my period is due….i dont have any of the symptoms anymore that i had in the first three weeks. THe only symptom i have is feeling a little sick sometimes but nothing major. The past three weeks i felt cramps like my period was coming and kept thinking my period would come early any day now. now two days before my period is due and i feel nothing…..i dont have any symptoms i have felt for the past three weeks my period would come and suddenly i feel like it wont come. I dont feel any PMS symptoms at all. I have watery dischage which sometimes has white in it Normally i do have this anyway before my period is due but it seems more than normal. For example sometimes this week i have felt like my period has started because i feel wet and go to the bathroom to find this watery discharge. Or if i cough or move my leg a certain way it seems to disrupt something and this water discharge appears. but i dont have my usual PMS symptoms as normal. Im wondering if any of this means im pregnant. Especially if i had sex in the ‘safe period’. but then why would i be testing positive for ovualtion for seven days before my period or is this just side effects from norethisterone