Hmmmm,... I'm not exactly sure what the question is you are asking.
When you say you think about the other partners daily what do you mean by that?
"were they better than me" ?
"were they bigger than me" ?
"I can't believe how many guys she's been with already" ?
It wouldn't surprise me if you thought about all 3 of these things really... It's quite normal to ask yourself questions about your girlfriends sexual past
But what you need to remember is that she's with YOU now. And it's important that you enjoy spending time with her...
If it really bugs you that much, why not try approaching the subject with your girlfriend? I've found some girls are pretty open about these sort of things and if she likes you that much she'll do her best to reassure you
give it a try if you like
Hope this helps