Oh it's the same for me and I'm a guy. I've found a girl I like for once, and she seems interested in me (she's at least not blatantly dismissive) but she doesn't initiate contact that often. Makes for bad mood swings. It's weird though, I'm insecure until I hear my phone making a sound. Then I'm totally cool, I don't have to rush off and read the text right away. Well, sometimes I do, because I fear the message will go along the lines of "Look Mr P, you're a great guy and all, but you're not my type..." and that's killing me.
It's all thinking about the details; "did I reply after a good enough delay, do I show correct amount of interest, etc." blah. I'm a newbie at this. But also, "will she feel detached from me because we don't talk all the time, like we're not supposed to be together?"
I'm trying to take my brain off of her by programming (doing my work), but big amounts of programming tend to make me asexual (or maybe it's the worrying, but I've noticed it's done so before), which would also drive her away and I would get the inevitable "great guy"-text :|