Do you have the insurance information and some cash for the copay? Because basically your health information is private, your dad does not have to know anything, legally. I understand there may be practical matters to work out (transportation?), but that's different. You're an adult, you can make your own appointment, you should have your insurance info on your person (ie in your wallet, with your other identification) at all times. And you should probably get your lady parts checked if you haven't ever yet - maybe dad won't bug you about THAT? Good luck.