Go see your OB/GYN and get a pregnancy test and a checkup! :) This will be the only way to determine whether or not you are pregnant.
That's a bit of a toughie. Theoretically, you should still have been protected, a single pill being only 8 hours late not being enough of a problem. But it sounds (by the breakthrough bleeding) like the hormones of the new pill are lighter than the old pill, not enough to protect you perfectly against shedding your endometrium. Does that also mean not enough to protect you from ovulating? Maybe but not absolutely?
What I'd do in your situation is call the 800 number on the packet insert that comes with the pills, and ask if breakthrough bleeding always / sometimes / never means a possibility of ovulation. I know they do usually suggest that if you have a missed pill or two, you should consider the month to be compromised and use back-up contraception. What I don't know is whether just a little breakthrough spotting means a risk of ovulation, or if you have to actually miss a pill.
You might also ask your doc the same thing, and while on the topic I'd ask about getting on a pill with a slightly higher level of protection, so it's not quite so sensitive to being only 8 hours late.
Good luck!
Thank you so much for the help. I'm on the birth control Loestrin. By the name of it, I assume it's a low estrogen pill. Does this give you any more information that you can pass on to me? By the way, I am going to call my doctor to set up an appointment tomorrow. I'd like to prepare myself with knowledge though if I can.
Sorry, I don't know much at all about the pill, it's been so long since I took one. :) Your better bet is the 800 number. Good luck!