2 weeks "together", I'm rly confused

I have a girlfriend for two weeks now. The thing is she broke up with her bf with whom she was together for a couple of years, and hooked up with me. It was really great, she told me she really liked me, and that I was the first guy she wanted to be together with after her bf (she broke up with him a couple of days before in order to be with me) and so it started. I know of her boyfriend and her from some mutual friends, so I know what she says is true. So, everythings great, and we're having a great time together for a week or so.

Ok, now, 3 days ago, she doesn't answer my call, and doesn't answer a text, so I chill out that day, and call her the next. She answers and says sth like "Sorry I didn't call you, I was out drinking with my friends!" (In my language male and female friends are said differently, she meant male friends) I was flabbergasted, but I was still cool, like ok, but please answer next time, lets meet up tomorrow. She says ok, and we decide to meet tomorrow around evening.

That night, she asked me on Facebook: "are you there" in 4:30AM, and I was sleeping.
The next day(yesterday), I call her, she doesn't reply. I send her a message "tonight 9pm? ", and she doesn't reply. She didn't reply whole day yesterday, and still ddidnt reply today.

What do I do? Maybe she hooked up with her bf again? Do I call her again? I mean its kinda desperate to still call her after this, but I'd like this to work.
-sidenote- currently i have exams and stuff and i study pretty much whole day everyday, so i don't have time to go and find new girls, so thats another reason I'm annoyed that this is happening. Please help, cheers!