 [ Symptoms ] i have irritationredness just on the inside of the tip of the penis does this sound like a uti or a std [ Disease ] if you are absolutely sure your boyfriend had a vasectomy and does not have any viable sperm anymore and he is the only one you are having unprotected sex with then the chance of pregnancy would seem to be zero there are dozens of different reasons why a woman would miss her period other than pregnancy so please see your gynecologist so you can be properly examined