Hello, Thanks for trusting us with your health concern. If you have always had regular menstrual cycles and do not use any regular contraception, you need to get proper clinical evaluation to detect the cause of the amenorrhea. You also need a sonogram of the pelvis, preferably in the trans-vaginal route to know the status of the pelvic organs. If pregnancy is excluded, other causes like hormone disturbances, infections, stress etc. should be evaluated. Insertion of the penis into the vaginal canal even without ejaculation can cause pregnancy as the pre-ejaculate contains enough sperm. Please see a specialist for further management. Hope this helps.