Hmm... To tell your girlfriend "I love you" is serious business and aren\'t exactly words to say because its the "right thing". My girlfriend and I for instance say it openly, all the time, anytime. We don\'t get all freaked out, and react so immaturely to it. It depends on how serious the relationship really is. If you can\'t even say "I love you" to one another, then maybe you should step back and look things over.
About sex, it should be just as easy to bring up, as saying that you love her. You should never really ask for sex, it should be something that she wants, and by asking it could put her on the spot, and deliver unwanted pressure. If she\'s not comfortable talking about it, chances are she isn\'t interested in doing it either.
Communication is key. Second to trust as a matter of fact. If you can\'t bring up either love or sex, then you have to make some sort of initiative. The longer it goes without you talking about, the harder it will get to bring it up. If she really cared for you, she wouldn\'t think that you were "weird" or "persistant" for asking about it. In fact, chances are she\'s thought about it too.