I am afraid my husband's vasectomy will fail ... need reurance?

I am 36 and my husband is 39. He had a vasectomy 12 years ago. Lately, I have been terrified of becoming pregnant. Being pregnant is not an option because we both have epilepsy (four doctors have told me my life is at risk) and I've known since age 6 that I never wanted kids. His general physician will not order a semen ysis and tried to reured me that the chances of his vasectomy failing are very slim to almost none. The doctor who did the vasectomy on him is a general surgeon and has performed many vasectomies before. (I cannot take the Pill because it causes severe headaches and my blood pressure to spike dangerously). My uncle did have a vasectomy in 1970 and it has never failed, so maybe I'm worrying for nothing?