Can somebody Help, Please? I could really use Some Advice...?

I lost my virginity to someone i really care about, but she wasnt a virgin.. And at first i was ok with that because i understand, but now it really bothers me.. Im happy with her and everything and she says she likes me more than her ex or anybody really.. but it just bothers me sometimes and it stays on my mind, That maybe im just another guy.. And i dont mean as much to her as she does to me.. Shes only been with 2 other guys, but What do you think? Will these thoughts go away? Am i overreacting to think like this? Any answers would be appreciated.. Thanks