I moved to australia 4 months ago and with the last 6 weeks I have been seeing this guy that I really like but things don't seem to be moving any further. How can I tell if he really likes me or if he is just using me for sex?

First off, stop having sex and see what he does. Put your foot down and have a serious talk with him to see where he stands.

After you talk, remember actions speaks louder than words. If he's not showing that he wants something more serious with you and continues to only want sex only, then you'll know that he's not really serious about you.