Jesus Christ! How old are you, man? What's w/ Nepali guys living w/ this "caveman" like mentality in today's world? You expect her to be a virgin simply because you happen to be one? 

I wouldn't worry about her past unless she had a shady past. People go through emotional and hormonal changes while growing up. More often than not, people also do uncontrollable acts (like you kissing your cousin albeit morality is a different issue). Having sex with people of other sex is one. 

You gotta suck it up and move on. If you really love her, accept her for who she is today instead of wasting your time pondering how often she kissed her ex and all that. 

You sound like a 20-22 year old.