I am 18 days late with my period.i am someone who has regular periods every month. lower back is painful and i just want to lay down. 3 hpg tests -ve?

Period "late".: At 33, delays in ovulation will result in both negative pregnancy tests and delayed menstruation. If "3 HPG tests" means you had serum HCG testing and they were negative, see your gyn physician for an exam and testing, and possible use of oral birth control (if no contraindications exist). Make sure you get a serum test for "human chorionic gonadotropin" (HCG) to be sure about pregnancy.