I once had a boyfriend who said that if he ever felt that he was losing his erection, he would imagine impregnating his partner and then her carrying his child. Such thoughts were like a guaranteed turn-on for him.
I don't think there is anything wrong with being aroused by the idea of pregnancy. (In an evolutionary perspective it seems very healthy. If only the giant pandas had pregnancy fetishes perhaps we could stop their extinction!
I think most people prefer sex without a condom, and I know I personally hate the birth control pill (and all its damn side effects.) I don't know your sexual lifestyle, but you could be putting yourself at great risk of STDs and unwanted pregnancies. I think you need to protect yourself in some way.
Can you control or override your desire for no contraceptives? There are many types available. Maybe one will interfere less with your animalistic/procreation fantasies?
Interestingly, a male contraceptive pill may be available in a few years' time. Then if you have a partner you can trust, he could be responsible for the contraception. And you could be free to fantasise that he's forgotten to take it, or that he deliberately threw it in the bin when you weren’t looking.
No diagnosis, lots of opinions, and a bunch of issues that I haven't quite figured out.