Well, i'm going to say that it took my bf and I 9 months before we had sex, and I was a virgin, so he introduced me to the world of sex, so to say!
Having sexual experiences with previous partners can make a person more comfortable with their body and more willing to engage in sexual activity, because they have fewer inhibitions about this supposedly "taboo" behavior. I think this unfortunately means that yes, her previous boyfriends may have influenced how she now feels comfortable having sex with you. That's not a bad thing; that's how people are; that's what people do! Don't feel jealous of her previous relationships, remember that she is with you,
now.
I'm glad to hear that you are having sex in conjunction to being in love; I believe that this is most important when being sexual with someone!
Just a question, how old are you two?