Is it going fast physically or emotionally? Either way I agree with PDM about telling him...because my bf is going fast emotionally. Everyone thinks he is pressuring me into marrying him, which he isn't but its mostly what he talks about...I think he has planned our entire life so far (the wedding, children and so on).
I just suggest slowing down because I just worry (for myself and you as well) that once I get that idea in my mind that we are getting married (especially this soon) that I will take it to heart and he will dump me and that will really hurt me...
Also physically going fast...(I'm not there yet so I can't really say but these are my fears) that I'll either regret doing physical things or that they will totally change the relationship. Oh and also pregnancy, diseases and other things if things get too physical...
I hope everything works out for you though:)