Your cycle has always been very regular. You were on the pill for a couple of years, but recently switched to condoms.
Your first three periods off the pill were exactly four weeks apart (like, down to the time of day they started). Now you are going on three days overdue for your period.
When do you panic?
FWIW: I POAS last night and it was negative (I have an emergency stash of dollar store tests) but who the hell knows if its to soon to tell.