I'm 16, My period came late last month by almost and week and is late this month by a little over week. I have been exercising a lot more and am very stressed a lot, but I've also had protected sex, and have made sure the condom was still intact every time. What is the explanation for this?

Stress and exercise can alter your period. Pregnancy is as ossibility as well. No form of both control is 100% effective.

Condoms of course have a 3 to 18 percent chance of failure, so if condoms are the only form of birth control you are using, pregnancy is always a very possible reason.

But since the period is just late, there are 100's of reasons, and at times it appears almost no reason, why periods are late. Stress is a major factor for being late.