What Causes Fainting, Headaches And Nausea While Having Normal Periods?

Hi.
I have been taking Yaz 28 day pack for about two years now. I take it every day at the same time, 7am, I have an alarm that wakes me to remind me. My boyfriend and I also use a condom and he pulls out. We like to be thoroughly careful.
May 22nd, I passed out at church and have been feeling bad since, headaches and slight nausea. I have had my May, June, and July periods. They all lasted 4-6 days which is normal for me. All involved my same amount of cramping. The nausea thing has scared me so two weeks ago, I took a pregnancy test, it came out negative. I took one yesterday as well (the day after my July period ended) and it was negative as well.
As I was thinking back, I remember the condom breaking once, but it was as we were getting started with our "activity" and noticed it and changed right away. I took the morning after pill the next morning just to be sure. I, however, cannot remember if this happened before I passed out or after.
I have read that some women can have their period while pregnant, and it scares me.
So...can I be pregnant?