Pregnant while on birth control?

No rude comments please! In September I missed 3 pills and started breakthrough bleeding that lasted 3 days, then had my normal "pill period" about 1 1/2 weeks later. When I was supposed to start my new pack I was unable to because of the hurricane, so I missed 3 days. I had already made a doctors appointment, so on the 4th day I went to the doc. and she switched my pill, and I started that night as she instructed me to. Now here's the problem I also had unprotected this whole time, I know its not the smartest thing, but we are engaged and live together so it wouldn't be the worst thing in the world if I were pregnant. I am due to start in a few days, and I just want to know how likely it is that I could be pregnant...