Delayed Period

Ladies,

Does anyone know how much exercise it takes to affect your period?

I have read that over-training can affect delay your cycle. Right now, I am three days late. Last week, to deal with extra stress (ironically, as that too can delay cycles) I added two extra hours of Pilates to my routine.

Is this enough to change my period? I am concerned, being that my boyfriend (of three years) and I, have almost finished college without having any pregnancy scares. This is a first for me!

When I overcame my eating disorder, my period became regular, even as I established a solid fitness pattern (Three days of Pilates/yoga plus dance/cardio kick boxing, two days of just cardio, one day of just Pilates/yoga and one rest day. My calorie intake at the end of the day is around 1200. I am 5'0 tall. Measurements/frame: 34-24-35.)

I know this could also be due to the two to three weeks of extra stress I experienced at work, but this sort of thing is so hard pinpoint its making me anxious. Is it possible this small change in my level of fitness is a factor?

Thanks for your support!