My girlfriend just started birth control. I'm lost.

Hello!

My girlfriend just started ortho tri-cyclen. As I understand it, there are 21 hormone pills and 7 placebo pills. When a woman begins taking the pill, she takes a hormone pill each day for 21 days, then a placebo pill each day for 7 days. She should menstruate during the week that she is taking placebo pills.

I also understand that there is a thing called a "day one start" in which you "begin taking the pill on the first day of your period." What does that mean? I assume the hormone pills are taken first. Is the "first day of your period" the day a woman starts bleeding or stops bleeding?

My girlfriend started taking the hormone pills on a Sunday, which incidentally was the day she stopped bleeding. Because you start with the hormone pills and end with the placebo pills and a woman should menstruate during the placebo pills, we assumed that starting the day she stopped bleeding meant that she was doing a "day one start."

However, I just read on wikipedia that a menstrual cycle is measured from the first day of menstruation. That would mean that to do a "day one start" a woman would take the first hormone pill on the day she started bleeding. But I thought the placebos were supposed to be taken during menstruation? Does that mean she did a day one start or not?

Because you're protected from pregnancy immediately when doing a day one start, we started having unprotected sex immediately. Now that I know a little more about it, I'm scared we did it wrong and she might be pregnant. It's been three weeks so I guess I'll know for sure soon. Can someone please straighten things out for me? Please don't assume I know what ANY menstrual cycle related terms mean because I absolutely do not.

THANK YOU!!!