I have absolutely nothing to add to Sue’s excellent post about contraception except to reiterate that your sexual health is absolutely your responsibility – and a partner who does not respect that, is not someone who deserves the privilege of sharing your bed.
And make no mistake, sex is a privilege. You can talk all you want about it being a bodily function and joke about notches on your bedpost, but you’re basically discussing the most invasive act your body will ever perform, short of childbirth, which 50% of you will never experience anyway.
I think I’ve linked to this calculator before but either way, it’s a good detail to keep in your head.
Speaking of respect, find a doctor who will treat you and your concerns with the same. If that’s not your family doctor, find a new one. You’re not paying her/him money for a moral lesson; you’re there for a medical opinion.
PS – remember to wash your hands. Before, if not after, but try for before and after. Of all the parts of your body, your pee-pee is the one you most definitely want to keep happy and fresh.