Can I get pregnant from having during placebo week of my birth control?

I've been taking a birth control pill called Aviane for about three months now. I've never missed a day and I always take it around the same time everyday. The first month was fine, but in the second and third months, I started having my period during the middle of the pack and not during the week of the placebo pills(...meaning I would ovulate during the placebos?) I just took my last placebo, so I'm out of birth control and I can't get a doctor's appointment to get a refill for another week (I know I should have gotten an appointment earlier, but I'm a college student and it's midterms). But this means that I'm going to have to stop the pill for a week or two, until I can get an appointment for a refill, then restart it. Whatever, it's my own damn fault. The problem is that I had with my boyfriend last night without a condom and he didn't pull out (Not smart, I know...also my own damn fault). Since I'm not on my period and I had during the placebo pills (2 weeks after my period) and I'm going to have no choice but to stop the pill, what are my chances of getting pregnant? Should I take Plan B?