why would you want a serious relationship when you're only 19? You should be experiencing life and having fun. You are only young once. Why are you so hung up on this guy after only 2.5 weeks?
You shouldn't even have any doubts at this point if the man were a right match. He is not ready to commit, yet you guys are doing sexual things? This is kinda backwards, and unhealthy from any perspective.
You need to take time to understand yourself before you jump into something serious. This guy is no good for you.