How is my Virgin gf Pregnant?

Ok, so my g/f and I are in tenth grade and we've been together for 3 years. We took chastity vows at church and are really committed. Sometimes I try and kiss her and she wont even do that! So I know she's serious. Well, somehow she's pregnant. She came and told me, and I looked at her stomach and sure enough, she was like 7 months prego. I dont know how this happened but she is. Ithink its the devil, because the only person who has a key to her chastity belt is her, but I assume the devil doesn't need a key. AND, before you ask, noone else knows about our chastity vows except for me and her so noone could've known and stolen her key. What should we do? How did this happen?

source