What do I do if I feel like my girlfriend and I are losing our connection?

I've been with this girl for about two months now. Until recently we always acted like best friends around each other. We made each other laugh, we always had something to talk about, etc. It's just recently that I've been feeling awkward around her, and I don't really even know why. We both admit that we've been seeing each other too much, almost every day for the first month and 3 to four times a week for about 2 weeks after that. We've both agreed to not see each other quite as much.This just happens with me, when I get comfortable, I get lazy, and I hate it. It just makes me yearn for the old times, when I could always make her laugh, when everything just felt so natural. Now it doesn't. It's just making me insecure and self conscious, and I feel like its weakening mine and her connection. We went to the zoo today, and on the whole ride up there I just found myself second guessing myself and saying something stupid as a response to everything she said. Why am I getting like this? How do I get back the connection that I feel like me and her used to have? I'm terrified to lose this girl. She tells me "I'm never leaving you", but that doesn't completely kill the fear, especially since I've been feeling like this.