Can a uti and yeast infection delay or stop your period?

No: Infections shouldn't delay or stop periods/menses. Take a home pregnancy test. If positive, go see your Family Doc for prenatal care. If negative, go see your doc anyway to determine what's happened to your periods, although they can be rather irregular when young (check out anovulatory cycles). And to discuss contraception options best 4 u (http://www.plannedparenthood.org/all-access/my-method).

Not usually: Any stress may slightly alter your cycle, but it won't usually sto it from coming.