Without reading all the replies etc… here is my opinion:
BE VERY CAREFUL DUDE!!! You are a young guy. The chances of you two being together a year from now are slim regardless of anything else. Don’t screw your whole life up over getting your dick wet or even less.
If it comes down to it I would ask her straight up what the deal is then ask for a std test with you giving one as well if needed. Explain your concerns when she goes off the wall with your questions.
Like I said, you are young, 98% chance this is not the woman you are going to spend the rest of your life with!!