I'm late.

If you're a woman, you should know what I'm talking about. Yup. My period's late. I usually have a fairly punctual 28 day cycle.Currently I am 4 days late. Should I be worried? Yes. Because if I am really pregnant, it is so off schedule. My youngest son is only going 2 next month. I barely have enough energy to keep up with them. From my experience, my energy level will drop whenever I'm pregnant. So I can't have less energy that what I have now. I'm so confused.