it probably is just late because of stress, from what you're telling me. but there is obviously no way to know without taking a test.
have a friend drive you. take a cab. take a bus.
and, read This readiness checklist. you shouldn't be having sex, honestly, if you can't plan for contingencies like this. if you can't get a ride to the drugstore, how can you get a ride to a clinic to care for your sexual health? you have to think about these things.
Boys and girls in America have such a sad time together; sophistication demands that they submit to sex immediately without proper preliminary talk. Not courting talk - real straight talk about souls - for life is holy and every moment is precious. I heard the Denver and Rio Grande locamotive howling off in the mountains. I wanted to pursue my star further. -Kerouac