I was a fitness instructor for many years and like the above poster said, most women don't discover pregnancy until around 5 - 6 weeks so I'm sure there's nothing to worry about.
Stress would cause more issues than exercise, especially if you normally exercise outside of pregnancy. Just relax, have a warm bath and put your feet up if you're worried, that will help with the stress too.
If you get any spotting, perhaps call your midwife or whatever you have over there, but this is only worst case scenario. You'll be fine.