I agree with Michelle, it was a bad idea to have sex with him, not necessarily because it was the first date, nor because you met him on the internet, more because you were always leaving after that weekend, so you were never going to be able to build up any kind of sexual connection beyond that one night... rather than it be the beginning of something it probably felt more like a one-nighter, which is a shame. The fact that you are counting the days until you go back and yet make no mention of him being excited for you to return is worrying, surely?
Bottom line, I'm going to suggest that having sex with a guy you don't know well enough to even maintain a text conversation with after the event is a bad idea. Sorry I can't be more positive or helpful but I think you're really just going to have to wait it out and see how things feel once you're back there. Good luck!