Feeling uneasy recently about how me and my gf came to start dating

(This got a little long, apologies. But i'd appreciate advice if you have time to read!) Me and my girlfriend met just over a year ago through a website that connects people studying each others languages, and we spoke on there for couple of months before deciding to meet in person. We had already gotten to the point where we were speaking quite a lot, so it wasn't a surprise when we hit it off pretty soon after meeting and starting dating. That was about 11 months ago now. My girlfriend likes to say it was 'destiny' that we were paired by chance amongst thousands of people, considering how seemingly well matched and perfect our relationship is now. Since then it's been great. I'm in my mid/late 20's (she's in her early-30's), and none of my previous relationships even come close to the feelings I have now for my girlfriend. And i'm confident that she feels the same. We just click, rarely argue, always have fun together whatever we're doing, and speak on the phone everyday without fail whenever we're apart. In short, she's awesome and I think we're both very happy. We've discussed both marriage and moving in together. Although, recently, we happened to get talking about the app that we met on. If we'd ever met anybody else through it, etc. I was open with her, I didn't really have anything worth hiding. But she was acting a little strange, like she didn't want to tell me everything. After a bit of egging on (i'm not the kind of person that cares about whats happened in the past, part of me just wanted her to be honest with me), I found out that she'd spoken to multiple guys who she'd told that she 'liked'. She also said that she had phone sex with one of them (we did that a couple of times before we met). So not at all different to what happened with us. She never met the other guys, which I do believe, the nature of the app means that 90% of the time the two people talking are in different countries. It was chance really that I happened to be moving close to where she lived not long after we started speaking. She told me it wasn't serious with the others since she knew they would never meet and she was just messing around as she'd been out of a relationship for 5 years. But I've started feeling a little strange about it. Like I said, she likes to call it 'destiny'. But now it just seems like she was talking to a handful of foreign guys (or many, I don't know), and telling them that she liked them, opening up the possibility of a romance if they ever were to meet in the future, but I just happened to be the most convenient since a couple of months after we started talking I was moving to her country and city. Feels more like I was headhunted than it does destiny. It just doesn't feel genuine some how. When she says that she was just messing around by having little online relationships, surely I was also one of those guys? Is my uneasiness justified, or is this my problem alone that I need to forget about? To be fair to her, she deleted all of her accounts on the website any anything similar almost immediately after we started dating, and severed all contact with any guys she used to speak to including guys who were just friends, despite me saying that it wasn't necessary. I've never had any reason to doubt her honesty since we've been dating. I love this girl to bits and everything that both me and her are currently doing (our work, studies, etc.) is with our future in mind, us living together (in a foreign country for me), marriage, etc. So I don't feel comfortable at all feeling this doubt towards her. Especially as it's not like things can be changed now. Any advice on how I should move past it? And should it involve speaking with her? Or would I risk creating even worse problems?

Thanks guys, You pretty much told me exactly what I needed to hear, and what I probably already knew before my worries took over. Of course her past is nothing to do with me, and I am not the kind of person that would ever hold it against her. I think anybody that is will struggle with relationships for life. Talking about stuff like that will never make a relationship stronger. We did speak briefly about the time around when we first met, and how our feelings for each other developed and became serious over time, just in an attempt to forget about the things I was thinking about. Things are good now, possibly better, as it's not something we'd ever spoken about in detail. As I had presumed, having gone through a messy break-up 5 years previously and this being her first relationship since, she had fears and trust issues to begin with, but they soon disappeared as we spent time together and I proved that I genuinely cared about her. Like I said in my original post, we have a great relationship, so i'm not going to threaten that in any way by bringing up stupid, irrelevant thoughts with her.