I think ive got your answer
A similar thing is the case with my girlfriend, she was with a much older guy than i am and that pissed me off at first when i learned about that but after thinking it just sorta made me feel insecure, and made me feel that im not what she wanted in the first place and on and on and on. So i put the issue in the back of my mind and went about my life with her. And after awhile of talking to her about our relationship i realized that theres a reason shes with me, its cause she wants to be with me, she really likes me, not that other guy and that she is with me right now, so i realized that me feeling all those negative things was truly pointless and makes no sensse to feel in the first place. Same with you, shes with you now. She tells you that your the one for her (provided you dont screw it up) and the guys before you dont matter, even if in your mind they are better than you, older or more experianced or even if she wanted them really badly none of it matters cause shes with you. And you have to appreciate that for what it is. And appreciate her.