Sounds to me like:
1. You essentially just met. You don't have a right to be "jealous" over any of this, and you hardly know her, but you're already calling her your "girlfriend". (Correct me if I've misunderstood. If you dated her for a while before this last week of boyfriend-girlfriend, how long was that?)
2. She's telling you about guys she's met, so she doesn't see you as a boyfriend figure. Even if you're "official" (which I'm unsure of, based on your response), you haven't been giving her the sense that you are in the role of her boyfriend. If you have only met her a week ago, then that's normal, and you shouldn't worry about it.
3. But it's also possible that the above is because you've been friend-zoneded, or are in the process of being friend-zoneded. You say you meet to just have fun and "be with each other", but what indicators do you have that she's attracted to you, have you escalated, and closed her? Have you been demonstrating interest? If not, step on that, pronto!
All in all, here's what the doctor prescribes, based on my understanding of the situation:
Don't worry about these other guys right now. Either she likes them or she doesn't, and there's nothing you can do about that. Besides, getting jealous or upset about it will seriously DLV and prove you as kind of needy, especially when you haven't been with this girl that long. Instead of focusing on her attraction to them, focus on her attraction to you, and make sure that that's in order. Go out, and make sure she's having more fun with you than with them.
And don't forget to escalate and show your interest, so that she'll eventually be afraid that if she's showing interest in other guys in front of you, that she may drive you away (and she won't want that because she likes you more!).