If my period comes on a week late , lighter then usual with clear discharge should i be running to my doctor?

Maybe (not) . . .: Walk, don't run. Actually, it really depends. Irregular cycles are very common when you're young. On the other hand, if you engage in unprotected sexual activity, then we worry about other issues such as infections. But as long as you're having your (irregular) menses, it's less likely that you're pregnant. But just in case, always use contraception & make him wear a condom.