Thats sods law for you, hmmm or maybe mother nature...

The only suggestion i have and im not entirely sure if your doctor would allow it for a non-health related reason, is to take progesterone pills for a couple days.

This will trick your body into thinking it is time to start menstruating. However, keep in mind the hormones can make you weepy and irritable....

Otherwise, you might just have to change your vacation dates...