I've been on BC for about 10 years now, I'm not perfect about taking it though. The first day of my bleed was October 8, however I missed the last active pill in that pack. I started the next pack a day late, I took 3 of the active pills and forgot 8 pills in a row - my fiancé and I have been having unprotected sex during this time. I now have nausea and cramping but no sign of any bleeding. Is it possible that I could be pregnant?

It is VERY possible you could be pregnant... if you are not taking the birth control pills as they are prescribed, they are not protecting you against pregnancy.
Even when you do take them as prescribed there is still a chance for pregnancy, as the pill is at best 97% effective. I got pregnant with my daughter while on the pill... and I never missed one!

If you are late on your period... time to take a HPT.