<human>: Give me the gist of the text in a nutshell

So I have been with my girlfriend for five months now, and everyone says were perfect for each other (I agree!). We're 17 years old and I love her very much.. but the past seems to be the recurring topic we argue about.

I don't have a past at all, she is my first everything--even first kiss. I never smoked or drank and I just don't really have any baggage. 

My girlfriend on the other hand is a different story. She has only been with one other guy (sexually) but it constantly irritates me and I find myself frequently asking her about stuff they've done (there isn't too much stuff) and I sadly admit I push it too far sometimes. 
She also has a light smoking and drinking past that bothers me--I tend to think about what she used to do in the past and it just ruins me. I get sad, and worst of all I get angry sometimes. I know it's the past and it's all over now.. But it bothers me to death. She admits that if I had done stuff it would bother her too.. So she understands why I push her about her past, Yet it still causes us arguments and one or two near breakups. 

Due to her past not being too thick, I know basically everything there is to know.. Yet it still bothers me. I love her so much and I want things to work, but we're facing this emotional roller coaster right now and it's just awful. 
I know I'm not just some crazy guy (or I hope not..!) because I've talked to 2 friends about this and they have nearly identical experiences with their girlfriends (although there's may be worse). 

At times I will try just not to say anything about her past because I want to move on.. But when there is something that I don't know it eats me alive and I eventually have to ask. I try to make it work by ignoring the questions I have but its just too hard sometimes. I'm looking for any and all advice.. And please please understand I want this to work with her. She's my first and hopefully my only love ever. Thanks for reading if you actually did and sorry for sloppyness: I typed this on my iPod.
<bot>: my girlfriend and I argue about her past and it's one of the only flaws in our relationship. I want to move on but it is frequently in my mind.