Delayed Period After Pill & Stress: Understanding Potential Causes

Question
I am in my early 30's and was on the pill for about 8 years, I have been off of it for about 2-2 1/2 years. I had unprotected sex with my boyfriend using the pull out method and thought I had a period that month. It was only a spot and then nothing more, this was about mid to late Sept. and I have not had a period that I can remember since. I have been under a lot of stress as well and I have had a delayed period in the past from stress but never this long. I have took a home test and a blood test both are negative. I have had signs of being pregnant such as going to the bathroom a lot, being very tired, depression(I'm normally upbeat), I'm feeling sick with certain smells, I get anoid very easily lately, my breasts have been tender, but I have not had morning or night sickness. My mother said she had negative home tests and blood tests before she showed a positive result for me. There is also a history of ovarian cancer in the family. Is it possible that I am pregnant or could it just be the extreme stress? Are there other things that could cause this to happen and should I be worried about the lack of my period in relation to the history of ovarian cancer?  

Answer
I would suggest that you take two blood tests for pregnancy, 48 hours apart. If you have a viable pregnacy, there will be a doubling of the results in 48 hours. If both results are less than 5, you are definitely not pregnant. If you have not had any period  since September, by now a sonogram will be accurate in showing if you are pregnant  or not. Discuss it with your doctor.